U.K. Prime Minister David Cameron has urged the authorities to consider blocking social-networking websites and messaging services

As a mean to quell riots, U.K. Prime Minister David Cameron has urged the authorities to consider blocking social-networking websites and messaging services during the country’s worst anarchism since the 1980s.

Cameron said that the government – working together with police, the intelligence services and companies – should 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.” He mentioned Research in Motion‘s BlackBerry Messenger service as one of the tools that were used by rioters.

“Free flow of information can be used for good, but it can also be used for ill,” Cameron said. “When people are using social media for violence, we need to stop them.”

Police have confirmed that they are investigating the use of social-networking services such as those operated by Twitter, Facebook and BlackBerry Messenger.

“All social media will be reviewed,” Cameron’s spokesman Steve Field said. “The government is still investigating how useful and practical blocking the websites and services would be and hasn’t reached any conclusion, he added. BlackBerry’s external U.K. spokespeople declined to comment on the possibility that authorities might shut or monitor user accounts, while Twitter spokespeople could not immediately be reached.

More than 1,300 people have been arrested in the U.K. since the disorder began on Aug. 6, with 888 of those in London.