Emboldened by this month's revolt that toppled the authoritarian leader of Tunisia, Egyptians have staged mass protests since January 25. The biggest demonstrations yet are planned for afternoon of January 28 after weekly prayers. 

Nobel Peace Prize winner Mohamed ElBaradei, who returned to Egypt from Vienna on January 27, has called for Mubarak to resign and said he would join the protests on January 28. 

Internet access was shut down across the country shortly after midnight. Mobile phone text messaging services also appeared to be partially disabled, working only sporadically. 

US State Department spokesman P.J. Crowley said in a message on Twitter: "We are concerned that communications services, including the Internet, social media, and even this tweet are being blocked in Egypt".

In Suez, which has been ground zero for some of the most violent demonstrations, police fired tear gas at protesters who hurled stones and petrol bombs into the early hours of January 28. Fires burned in the street, filling the air with smoke.