The social network had introduced a temporary ban in May following complaints that the clips could cause long-term psychological damage.

The US firm confirmed it now believed its users should be free to watch and condemn such videos. It added it was, however, considering adding warnings.

One suicide prevention charity criticised the move.

"It only takes seconds of exposure to such graphic material to leave a permanent trace - particularly in a young person's mind," said Dr Arthur Cassidy, a former psychologist who runs a branch of the Yellow Ribbon Program in Northern Ireland.

"The more graphic and colourful the material is, the more psychologically destructive it becomes."

Facebook allows anyone aged 13 and above to be a member.

Its terms and conditions now state that it will remove photos or videos that "glorify violence" in addition to other banned material, including a woman's "fully exposed breast".

New rules

The BBC was alerted to Facebook's change in policy by a reader who said the firm was refusing to remove a page showing a clip of a masked man killing a woman, which is believed to have been filmed in Mexico It was posted last week under the title, Challenge: Anybody can watch this video?

"Remove this video too many young innocent minds out there shouldn't see this!!!" wrote one user in the comments section below.

"This is absolutely horrible, distasteful and needs to be removed... there are too many young minds that can see this. I'm 23 and I'm very disturbed after seeing a couple of seconds of it," wrote another.

The social network later confirmed it was allowing such material to be posted again.

"Facebook has long been a place where people turn to share their experiences, particularly when they're connected to controversial events on the ground, such as human rights abuses, acts of terrorism and other violent events," said a spokeswoman.

"People are sharing this video on Facebook to condemn it. If the video were being celebrated, or the actions in it encouraged, our approach would be different.

"However, since some people object to graphic video of this nature, we are working to give people additional control over the content they see. This may include warning them in advance that the image they are about to see contains graphic content."

Facebook originally pulled decapitation videos after the Family Online Safety Institute - a member of its Safety Advisory Board - complained that they "crossed a line" bearing in mind how young some of its members were.

The long-awaited cross-platform offering, which was delayed after issues arose following the initial launch last month, is now being rolled out in a phased manner.

"To help manage this unprecedented pent-up demand for BBM, we are implementing a simple line-up system to ensure a smooth rollout," Andrew Bocking, who heads the BlackBerry's BBM business, said in a blog post on the company's website.

BlackBerry said last week that 6 million Android and iPhone customers had pre-registered for the launch.

Le Monde said the U.S. National Security Agency (NSA) recorded 70.3 million items of French telephone data between December 10, 2012 and January 8, 2013 and had collected tens of thousands of French phone records.

Its targets appeared to be individuals suspected of links to terrorism, but also people tied to French business or politics, the paper said.

The allegations tested France's relations with Washington just as U.S. Secretary of State John Kerry arrived in Paris for the start of a European tour over Syria.

French Foreign Minister Laurent Fabius said the Le Monde report on Monday had revealed "unacceptable practices".

"We have extremely useful cooperation with the United States in the struggle against terrorism, but this cooperation does not justify everything," Fabius told reporters on the sidelines of a meeting with EU counterparts in Luxembourg.

"So we've asked the United States to provide clarifications, explanations and justifications extremely quickly," he added.

Speaking to reporters in Paris, Kerry declined to comment on Washington's intelligence-gathering as a matter of policy, but said that the United States would hold talks with France and other allies on the issue.

"Our goal is always to try to find the right balance between protecting the security and the privacy of our citizens and this work is going to continue as well as our very close consultations with our friends here in France," Kerry said.

The U.S. embassy in Paris said Ambassador Charles Rivkin had promised Fabius's chief of staff that he would convey France's concerns to Washington.

Rivkin declined immediate comment but stressed that U.S.-French ties were close. "This relationship on a military, intelligence, special forces ... level is the best it's been in a generation," Rivkin told Reuters as Kerry arrived in Paris.

The scope of the NSA's alleged surveillance programme may overshadow a relationship that has appeared strong in recent years as Paris and Washington cooperated closely on national security and united to bring pressure on Syrian President Bashar al-Assad to quit.

In July, Paris prosecutors opened a preliminary inquiry into the NSA's programme, known as Prism, after Britain's Guardian newspaper and Germany magazine Der Spiegel revealed wide-scale spying by the agency leaked by former NSA contractor Edward Snowden.

Combined shipments of computers, tablets and mobile phones will reach 2.32 billion units in 2013, a 4.5 percent increase on 2012, Gartner forecast. Shipments of tablets are expected to rise 53.4 percent to 184 million.

Traditional desktop and laptop computers will continue to decline, with shipments forecast to total 303 million units, an 11.2 percent drop on 2012, the research group said.

The mobile phone market will continue to experience steady growth, it said, with shipments projected to increase by 3.7 percent to more than 1.8 billion units, it said.

Price competition is strongest for the smaller, 7-inch, tablets, Gartner said.

The governor's decision, which came just hours after same-sex couples began marrying in New Jersey, removed a legal challenge that could have left those newlyweds in limbo until the courts ruled on an appeal previously filed by the Christie administration. That appeal was due to be heard in January.

But Christie, in a reversal, asked acting Attorney General John Hoffman to withdraw the state's appeal on Monday, the governor's office said in a statement.

"Although the governor strongly disagrees with the court substituting its judgment for the constitutional process of the elected branches or a vote of the people, the court has now spoken clearly as to their view of the New Jersey Constitution, and, therefore, same-sex marriage is the law," the statement said.

By a 2-1 margin, New Jersey voters in a poll earlier this month said Christie should drop the appeal.

The governor, who is heavily favored to win re-election next month and believed to be eyeing a White House run in 2016, has said the issue should be decided in a popular referendum.

The former federal prosecutor has enjoyed bipartisan popularity since he famously boosted the re-election chances of President Barack Obama last year by embracing his response to Superstorm Sandy.

New Jersey voters applauded Christie for putting the state's interests ahead of politics, although national Republicans responded to the gesture with dismay.

Christie has built a reputation for reaching across party lines in instances such as his friendship with Newark Mayor Cory Booker, a liberal Democrat elected last week to the U.S. Senate. Appearing as a tough Republican executive who can win a strong Democratic following may give Christie a boost on the national stage, observers have said.

Christie vetoed a gay marriage bill in 2012, but the issue took on renewed urgency three weeks ago when Superior Court Judge Mary Jacobson in Trenton ruled in favor of couples who had challenged the state's civil union law. The judge found that the law unfairly restricted federal benefits that are guaranteed for married couples.

Jacobson's decision made New Jersey the first state to lift a gay marriage ban as a result of the U.S. Supreme Court's decision in June to strike down the federal law defining marriage as between a man and a woman.

With many Americans experiencing error messages and long waits in trying to sign on to healthcare.gov, Republicans in Congress who have fought the Affordable Care Act since before its 2010 passage renewed calls for a delay in the rollout of the law in order to fix it.

Obama surrounded himself in the White House Rose Garden with a group of people who have successfully navigated the system. In a speech, Obama declared himself frustrated with the technical glitches and vowed to get them repaired.

"Nobody's madder than me about the fact that the website isn't working as well as it should, which means it's going to get fixed," said Obama, who counts the law as his most significant domestic policy achievement.

Online insurance exchanges were launched on October 1 under the law, often called "Obamacare," to offer health insurance plans to millions of uninsured Americans. But many people trying to shop for health insurance at healthcare.gov have failed to make it through the system despite repeated tries.

Republicans also renewed their demand that Obama's top health adviser, Health and Human Services Secretary Kathleen Sebelius, testify this week before a House of Representatives oversight hearing about the website's problems.

"Americans didn't get any answers from the president today, but the House's oversight of this failure is just beginning," said House Speaker John Boehner, the top Republican in Congress.

A Sebelius spokeswoman said the HHS secretary would testify next week - not this week - due to a scheduling conflict.

"We are in close communication with the committee and have expressed our desire to be responsive to their request," Sebelius spokeswoman Joanne Peters said.

The White House said last week that Obama still has "full confidence" in Sebelius, whose department is responsible for implementing the law.

Saudi Arabia rejected a coveted two-year term on the council on Friday in a rare display of anger over what it called "double standards" at the United Nations. Its stance won praise from its Gulf Arab allies and Egypt.

Saudi Foreign Minister Prince Saud al-Faisal hosted a lunch for Kerry at his private residence in Paris on Monday. U.S. officials said Washington and Riyadh shared the goals of a nuclear-free Iran, an end to Syria's civil war and a stable Egypt.

A senior State Department official told reporters after the lunch that Kerry cited the advantages of being on the 15-member body, which can authorize military action, impose sanctions and set up peacekeeping operations.

"Secretary Kerry conveyed that while it is Saudi Arabia's decision to make, the U.S. values Saudi Arabia's leadership in the region and the international community," the U.S. official said.

"A seat on the UNSC affords member states the opportunity to engage directly," the official added.

The council has been paralyzed over the 31-month-old Syria conflict, with permanent members Russia and China repeatedly blocking measures to condemn Syrian President Bashar al-Assad, a longtime ally of Riyadh's regional arch-rival Iran.

Saudi Arabia backs the mostly Sunni Muslim rebels fighting to overthrow Assad. The Syrian leader, whose Alawite sect is derived from Shi'ite Islam, has support from Iran and the armed Lebanese Shi'ite movement Hezbollah. The Syrian leader denounces his foes as al Qaeda-linked groups backed by Sunni-ruled states.

Riyadh's frustration with Russia and China now extends to the United States, not only over Syria, but also over Washington's acquiescence in the fall of Egypt's Hosni Mubarak in 2011 and its new quest for a nuclear deal with Iran.

"I didn't really get the point of it at all," said the Las Vegas resident. "Most of them were people I wasn't interested in hearing what they had to say anyway." He said, however, that he does check Facebook every day to see what his friends are up to.

Hovasse's experience highlights a risk for investors as Twitter Inc marches towards this year's most anticipated initial public offering in the United States, expected to begin trading on the New York Stock Exchange in mid-November.

According to a Reuters/Ipsos poll, 36 percent of 1,067 people who have joined Twitter say they do not use it, and 7 percent say they have shut their account. The online survey, conducted October 11 to 18, has a credibility interval, a measure of its accuracy, of plus or minus 3.4 percentage points.

In comparison, only 7 percent of 2,449 Facebook members report not using the online social network, and 5 percent say they have shut down their account. The results have a credibility interval of 2.3 percent.

People who have given up on Twitter cite a variety of reasons, from lack of friends on the service to difficulty understanding how to use it. Twitter declined to comment for this story, saying it is in a quiet period ahead of its IPO.

Twitter's attrition rate highlights a challenge that has dogged the online messaging site over the years: while it has managed to enlist many high-profile and avid users, from the Pope to President Barack Obama, Twitter has yet to go truly mainstream in the way Facebook has.

Convincing ordinary people to think of Twitter as an indispensable part of their lives is key to the company's ability to attract advertisers and generate a profit.

Twitter reported it had 232 million "active" users - people who access the service at least once a month - at the end of September, up 6.1 percent from the end of June. Twitter's quarter-over-quarter growth in active users has not exceeded 11 percent since June 2012.

When Facebook was a similar size, its active users were increasing by more than 20 percent every quarter, and it was not until the social network neared the half-a-billion member mark that its user growth decelerated to 12 percent.

"Luckily, we have instruments of torture, which we will use if necessary," Andreas Mundt, the president of the German cartel office, was quoted as telling daily Sueddeutsche Zeitung.

A struggle with competition authorities in its second-largest market after the United States would add to Amazon's woes.

Its German operations have been rattled by a dispute over employees' pay and a trade union has warned that staff could strike during the Christmas holiday season.

"The terms of Amazon's Marketplace in effect obstruct competition," Mundt said, according to a pre-release on Sunday of the newspaper's Monday edition.

"We are in talks with Amazon to eliminate these impediments to competition...If necessary, we will issue a crystal clear decree."

Separately, Amazon has been criticized over its tax payments and leading policy makers have called for a new German government to crack down on tax avoidance by multinational firms without waiting for its European partners to act.

Fresh from the U.S. budget battles, Obama on Monday will turn his attention to convincing Americans that the healthcare program can be fixed, despite the initial problems.

Speaking on NBC's "Meet the Press" on Sunday, Treasury Secretary Jack Lew said the administration was determined to repair the technical glitches in the online insurance exchanges that are a central part of the program known as "Obamacare," which launched on October 1.

"I think that there's no one more frustrated than the president at the difficulty in the website," Lew said. He said the U.S. Department of Health and Human Services "has got plans to fix this and it has to fix this. It has to be done right."

Obama told aides in a recent Oval Office meeting that the administration had to take responsibility for the fact that the website was not ready on time. He is expected to address that in his remarks on Monday.

Administration officials are expected to travel the country in the coming weeks to encourage people to sign up on the exchanges, targeting areas where there are high percentages of uninsured, according to one official.

The Patient Protection and Affordable Care Act is expected to provide private health coverage to an estimated 7 million uninsured Americans through the new online marketplaces that opened for enrollment in all 50 states on October 1.

But the website, healthcare.gov, the administration's online portal for consumers in 36 states, was hobbled by technical problems - including error messages, garbled text and delays loading pages.

Administration officials blame the problems partly on an unexpectedly high volume of visitors in its first 10 days. According to the Department of Health and Human Services, there were more than 19 million visits to the website.

"We are committed to doing better," the department said in a blog post on Sunday.

Despite the problems, it said, other parts of the system were function well.

"Individuals have been able to verify their eligibility for credits, enabling them to shop for, and enroll in, low- or even no-cost health plans," the department said.

"We have updated the site several times with new code that includes bug fixes. Our team has called in additional help to solve some of the more complex technical issues we are encountering."

DAMAGE CONTROL

Late on Saturday the White House reported nearly half a million Americans had applied for health insurance through the federal and state exchanges provided by Obamacare.

Speaking on NBC's "Meet the Press" program, Lew said he was confident the economy, which he described as resilient, would recover from the 16-day partial shutdown of the federal government.

He described events leading to the shutdown, which eroded both business and consumer confidence, as a political crisis rather than an economic one.

"We know that from the shutdown, there was a loss of economic activity," Lew said. "We need to make sure that government does not go through another round of brinkmanship. This can never happen again."

A last minute deal in Congress pulled the country from the edge of an unprecedented debt default. It restored government funding through January 15 and extended its borrowing authority through February 7, though the Treasury Department might be able to stave off a default for several weeks past that point.

There are worries that Wednesday's deal may have set the stage for another standoff in the future.

Lew, the administration's front man during the stalemate over increasing the country's borrowing limit, has attempted to separate the debt ceiling from other policy conditions.

"I think the message that we have to send going forward is that there was a turning point on Wednesday night and this won't happen again. It can't happen again," he said.

Similar sentiments were echoed by Republican John McCain, who told the NBC's "Meet the Press" program that the shutdown hurt his party. McCain said there would be no second shutdown.

"Those involved in it went on a fool's errand, that's just a fact," McCain said. "This has harmed the lives of millions of people and thousands of people in my state ... I have an obligation to them to try to prevent that from happening."

Lew did not quantify the damage to the economy.

Economists estimate the shutdown shaved as much a half a percentage point from fourth-quarter gross domestic product growth, with much of the direct hit through the loss of output from the federal government.

"It took an economy that is fighting hard to get good economic growth going, to create jobs for the American people, and it took it in the wrong direction," Lew said. "This one was a little bit scary because it got so close to the edge."

There's a need to shift the focus away from fiscal policy, Lew said, arguing that the budget deficit as a share of the economy has been reduced significantly.