Clashes occurred in Egypt between anti-government protesters and riot police outside the presidential palace in Cairo on Friday.
Protesters threw rocks and petrol bombs at security forces. Riot police used tear gas and water cannon to try to drive them back.
Thousands also rallied in Port Said at the northern end of the Suez Canal, where football riots killed 74 people a year ago.
The protesters accuse President Mohammed Mursi of betraying the 2011 uprising - a claim he denies.
They chanted "Leave, leave, Mursi!" outside the palace in Cairo. Some of the demonstrators then began throwing Molotov cocktails over the palace walls and lighting fires in the streets.
The BBC reports the current unrest began on 24 January in Cairo on the eve of the second anniversary of the revolution and has spread to several cities.
On Tuesday, General Abdul Fattah al-Sisi warned that the crisis could lead to the collapse of the state.