LONDON (Reuters) - Britain is considering disrupting online social networking such as Blackberry Messenger and Twitter during civil unrest, PM Cameron said Thursday, a move widely condemned as repressive when used by other countries. Egyptian authorities shut down mobile and Internet services in January during mass protests against then-President Hosni Mubarak, while China is quick to shut down online communication it sees as subversive. Police and politicians have said online social networks, in particular Research in Motion's popular Blackberry Messager, were used by rioters and looters to coordinate during four days of disorder across England.