Egypt appears to have clamped down on web services, such as Twitter, that have been used to help organise anti-government protests in Cairo.
Twitter confirmed that its service has been blocked in Egypt on Tuesday from around 1600GMT.
A Swedish mobile video site called Bambuser also reported that it had been blocked around the same time.
However, the Facebook page used to co-ordinate many of the protests has remained online.
Facebook has not said whether it has implemented any technical measures to keep the site up and running but a spokesperson said that it was "seeing consistent levels of traffic".
BBC News - 26 January 2011 | Read Full Report