Protesters and riot police fought pitched battles in Cairo on Sunday as clashes sparked by the failure of Egypt's military rulers to prevent deadly football-linked violence raged into a fourth day.
Hundreds of riot police blocked off roads leading to the interior ministry headquarters in the centre of the capital, firing tear gas to keep dozens of rock throwing protesters at bay.
Police erected a concrete block wall on Mansur street, which has become the nerve centre of the deadly clashes, while entrenching themselves behind coils of barbed wire on other roads.
Protesters lobbing stones and petrol bombs at the police lines cheered when their comrades brought back a captured man they said was a plainclothes officer. Others tried to shield him from the protesters' kicks and punches.