Further protests over an anti-Islam film have taken place outside the US embassy in Cairo.
Police fired warning shots and tear gas in a bid to keep the protesters away from the building.
They responded by throwing petrol bombs as the security forces tried to drive them back towards the nearby Tahrir Square.
Egyptian officials said six police officers were injured in the clashes.
The country’s largest political force, the Muslim Brotherhood, has called for peaceful protests to be held nationwide on Friday.
Similar rallies have been held in other countries, including Libya and Tunisia.
Dozens of Salafist protesters gathered outside the US Embassy in the Tunisian capital, Tunis, on Wednesday
Some threw stones and chanted slogans such as “Death to America”.