Five people have been shot dead in the Egyptian city of Suez during nationwide protests against President Mohamed Mursi on the second anniversary of the uprising that toppled Hosni Mubarak.
One of the dead was a member of the security forces, medics said.
Another 280 civilians and 55 security personnel were injured, officials said, in demonstrations fuelled by anger at the president and his Islamist allies in the Muslim Brotherhood.
Thousands of opponents of Mursi massed in Cairo's Tahrir Square - the cradle of the revolt against Mubarak - to rekindle the demands of a revolution they say has been hijacked by Islamists who have betrayed its goals.
Street battles erupted in Cairo, Alexandria, Suez and Port Said. Arsonists attacked at least two state-owned buildings as symbols of government were targeted. An office used by the Muslim Brotherhood's political party was also torched.
The 25 January anniversary laid bare the divide between the Islamists and their secular rivals.
This schism is hindering the efforts of Mursi, elected in June, to revive an economy in crisis and reverse a plunge in Egypt's currency by enticing back investors and tourists.
Inspired by the popular uprising in Tunisia, Egypt's revolution spurred further revolts across the Arab world.
However the sense of common purpose that united Egyptians two years ago has given way to internal strife that had already triggered bloody street battles last month.
The Brotherhood decided against mobilising for the anniversary, wary of the scope for more conflict after December's violence, stoked by Mursi's decision to fast-track an Islamist-tinged constitution rejected by his opponents.
The Brotherhood denies accusations that it is seeking to dominate Egypt, labelling them a smear campaign by its rivals.