British Prime Minister David Cameron proposed Thursday a ban of online social networks, Blackberry Messenger and Twitter during civil unrest.

"We are working with police, the intelligence services and industry to look at whether it would be right to stop people communicating via these websites and services when we know they are plotting violence, disorder and criminality," the prime minister told Parliament during an emergency session prompted by this week's riots.

After four nights of rioting and looting in London and elsewhere, some police, politicians and media organizations singled out BlackBerry's messaging network as being a useful aid for troublemakers.

Using BlackBerry handsets – the smartphone of choice for 37 percent of British teens, according to last week's Ofcom study – BBM allows users to send one-to-many messages to their network of contacts, who are connected by "BBM PINs," The Guardian reports.

Many of the rioters favored Canadian firm Research in Motion's BBM over Twitter and other social media because its messages are encrypted and private.

It's an "encrypted, very secure, safe, fast, cheap, free, easy way for disaffected urban youth to spread messages for the next targets", said Mike Butcher, editor of TechCrunch Europe and digital adviser to London Mayor Boris Johnson.

One BBM broadcast sent on Sunday, which has been shown to The Guardian by multiple sources, calls on "everyone from all sides of London" to vandalize shops on Oxford street, according to the London newspaper.

RIM said Wednesday that it has "engaged with the authorities to assist in any way we can." The Metropolitan Police, known as Scotland Yard, have said that they are monitoring social media sites such as Twitter and Facebook.

The company said Monday that it cooperates with all telecommunications, law enforcement and regulatory authorities, but it declined to say whether it would hand over chat logs or user details to police.

"As in all markets around the world where BlackBerry is available, we cooperate with local telecommunications operators, law enforcement and regulatory officials," said Patrick Spence, managing director of global sales and regional marketing at RIM.

In August of last year, a source close to talks between RIM and Saudi authorities said the company had agreed to hand over information that would allow monitoring of BBM.

Online social media was also widely used by members of the British public in recent days to help others avoid trouble spots and to coordinate a cleanups after the rioting.

BBM has more than 45 million active users worldwide, 70 percent of whom use it daily, sending billions of messages, pictures and other files in total every month.