One person was killed and 676 injured yesterday when police clashed with thousands of protesters for control of Cairo's Tahrir Square.
The violence erupted only nine days before Egypt's first elections since President Hosni Mubarak's removal from office in February.
In scenes reminiscent of the 18-day uprising, protesters and police forces hurled rocks at each other, and crowds climbed on to an armoured police truck, setting it alight.
Witnesses said the violence began when riot police dismantled a camp set up to commemorate protesters killed in February's uprising. Some 200 demonstrators were attacked.
Tens of thousands of people had gathered in Tahrir Square on Friday to denounce Egypt's ruling military council, which has been criticised for its handling of Egypt's bumpy transition to democracy. Protesters accuse the military of trying to give themselves special powers over the future elected government.
Yesterday's confrontation was one of the few to involve police since the uprising. The black-clad police were a hated symbol of the Mubarak regime.
Protests continued into the night, with crowds chanting: "Riot police are thugs and thieves."