Concerned over the role played by the social media in inciting unrest during the recentriots in England, a top British Parliamentary body headed by Indian- origin MP Kieth Vaz asked the bosses of Twitter, Facebook and BlackBerry to appear before it.

"Today I have written to the Chairmen of Twitter, Facebook and BlackBerry because it is absolutely clear that the new media had a role in the number of people who turned up at various places," Vaz, Chairman of the influential Home Affairs Committee of the House of Commons, said here.

"It is clear that people were using the private BlackBerry network to announce that there is going to be riot in such and such street and such and such time," he said.

The unrest had been branded ''BlackBerry riots' because trouble-makers mainly used the BlackBerry Messenger system to communicate instantly with other feral groups and coordinate attacks in various areas in London.

"This is a new phenomenon to the world and it certainly challenges all police forces," Vaz said.

For looters and rioters in England, the communication tool of choice has apparently been BlackBerry Messenger (BBM) which acted as their private, encrypted social network for rallying around potential targets, British media reports said.

The Scotland Yard has already said that it was tracking down the persons who posted "really inflammatory and inaccurate" messages on social media, that were used to organise and coordinate the riots in London.

BBM, as it is known is an instant messaging application, allows users to communicate in a similar way as text messaging, but effectively without charge, as traffic is exchanged via the Internet.

"I am not criticising the new media and I am saying this as a matter of fact," Vaz said, adding that it was important to deal with the issue.