Facebook and BlackBerry-maker RIM confirmed their participation in the meeting last week, but at the time a Twitter spokesperson only said, "We'd be happy to listen."
After it became clear that some rioters were using social media and BlackBerry messenger to coordinate violence, UK Prime Minister David Cameron told Parliament that the government was examining whether to ban suspected troublemakers in the riot from using social media and other digital communication tools.
"When people are using social media for violence we need to stop them," he said, to the chagrin of many free speech activists. "So we are working with the 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."