While social media networks have been partially blamed for the spread of rioting in England last week, such mobile communications can also be used to prevent such acts of violence.

London police claim that they have prevented attacks by rioters on two prominent locales – Oxford Street and the 2012 Olympic site -- by spying on chatter over Blackberry and Twitter accounts.

Lynne Owens, the Assistant Commissioner for Metropolitan Police, told a committee of MPs that some officers became aware of potential trouble by monitoring chatter on Twitter and BlackBerry Messenger (BBM).

"Through Twitter and BBM there was intelligence that the Olympic site, that both Westfields [shopping centers] and Oxford Street were indeed going to be targeted," Owens told the home affairs select committee.

"We were able to secure all those places and indeed there was no damage at any of them."

However, the Acting Commissioner Tim Godwin said that while social network messages sometimes provide valuable intelligence, they are also misleading – and much of it is inane chatter.

"We did contemplate, I contemplated, asking the authorities to switch it off. The legality of that is very questionable and additionally, it is also a very useful intelligence asset," he said.

"So, as a result of that, we did not request that that was turned off, but it is something that we are pursuing as part of our investigative strategy."

Meanwhile, while London police sift through a huge amount of social media correspondence, BlackBerry has offered to help with the investigation and hand over data to the authorities (a measure which itself led to cyber attacks on the company’s own website).

In addition, Sir Hugh Orde, president of the Association of Chief Police Officers, told MPs that these riots were something completely new, which police had never faced before.

He told the committee that the violence was "multi-site" and "far more spontaneous", while there was almost "non-existent pre-intelligence" which might have helped police get a handle on the disturbances.