David Cameron has told parliament that in the wake of this week's riots the government is looking at banning people from using social networking sites such as Twitter and Facebook if they are thought to be plotting criminal activity.
The prime minister said the government will review whether it is possible to stop suspected rioters spreading online messages, in his opening statement during a Commons debate on Thursday on the widespread civil disorder for which MPs were recalled from their summer recess.
Answering questions after his statement, Cameron said the home secretary, Theresa May, will hold meetings with Facebook, Twitter and Research In Motion within weeks to discuss their responsibilities in this area.
The prime minister also said that broadcasters – including the BBC and Sky News – have a responsibility to hand unused footage of the riots to police.
Past attempts to force broadcasters to hand over their footage have been met with fierce resistance. On Wednesday, the BBC's head of newsgathering, Fran Unsworth, said voluntarily giving unused footage to the police would damage broadcasters' editorial independence.
"I have also asked the police if they need any other new powers."
"Police were facing a new circumstance where rioters were using the BlackBerry Messenger service, a closed network, to organise riots," he said. "We've got to examine that and work out how to get ahead of them."
The prime minister made the announcement as he vowed to do "whatever it takes" to restore order to the nation's streets after four nights of unprecedented civil unrest.
A move to disconnect potential rioters would mark a huge shift in Britain's internet policy, with free speech advocates likely to accuse the government of ushering in a new wave of online censorship.
Scotland Yard has made a string of arrests of people suspected of inciting the violence across England by using BlackBerry Messenger, Twitter and Facebook.
Cameron urged Twitter and Facebook to remove messages, images and videos that could incite more unrest across the country. "All of them should think about their responsibility and about taking down those images," he said.
"There was an awful lot of hoaxes and false trails made on Twitter and BlackBerry Messenger and the rest of it. We need a major piece of work to make sure that the police have all the technological capabilities they need to hunt down and beat the criminals."
Jim Killock, the executive director of online advocacy organisation Open Rights Group, said Cameron risked attacking the "fundamental" right of free speech.
"Events like the recent riots are frequently used to attack civil liberties. Policing should be targeted at actual offenders, with the proper protection of the courts," Killock added.
"How do people 'know' when someone is planning to riot? Who makes that judgment? The only realistic answer is the courts must judge. If court procedures are not used, then we will quickly see abuses by private companies and police. Companies like RIM must insist on court processes.
"Citizens also have the right to secure communications.  David Cameron must be careful not to attack these fundamental needs because of concerns about the actions of a small minority."
Hampshire police on Wednesday arrested three people on suspicion of using Twitter and BlackBerry Messenger to incite violent disorder in Southampton. Those arrests are thought to be the first directly linked to the use of the popular BlackBerry instant messaging service. A number of arrests have been made of people suspected of inciting violence on Facebook.
David Lammy, the MP for riot-stricken Tottenham, on Tuesday appealed for the BlackBerry maker Research In Motion to shut off its BlackBerry Messenger service after claims that it played a key role in organising the unrest.
Research In Motion declined to comment.
