Egypt opposition groups start Tahrir Sq sit-in
23 November 2012 Last updated at 21:25 GMT
Thousands of Egyptians are protesting over a new decree granting President Mohammed Mursi sweeping powers.
Earlier, Mr Mursi delivered a defiant speech to supporters outside his palace, pledging to protect the country's revolution and lead Egypt to freedom and democracy.
Opposition groups have accused him of behaving like a dictator, and begun a sit-in in Tahrir Square - the symbolic home of the revolution that toppled Hosni Mubarak nearly two years ago.
Jamie Robertson reports.