EGYPT'S army deployed tanks outside the presidential palace after a night of deadly clashes between opponents and supporters of President Mohamed Morsi. Three tanks and three armoured personnel carriers at the front gate of his palace were ringed by hundreds of Dr Morsi's partisans chanting slogans.
Five people were reported killed and nearly 350 injured as mobs threw rocks and petrol bombs in the streets around the palace.
It was the first serious outbreak of violence between political factions since the revolt against former president Hosni Mubarak began nearly two years ago.
Three senior advisers to Dr Morsi, Egypt's first elected President, resigned during the clashes and Prime Minister Hesham Kandil implored both sides to pull back to make room for talks.
The scale of the clashes raises doubts about Dr Morsi's attempt to hold a referendum on December 15 to approve a draft constitution approved by his Islamist allies despite opposition objections.
Periodic gunshots could be heard overnight on Wednesday from the front lines of the fight. Riot police tried to fight off or break up the crowds with tear gas, but by late evening the security forces had all but withdrawn.
''This is not a fight for an individual, this is not a fight for President Morsi,'' a spokesman said through a loudspeaker on the top of a moving car in a city square on the Islamist side of the city. ''We are fighting for God's law, against the secularists and liberals.''
Protesters reportedly set fire to Muslim Brotherhood political offices in the cities of Suez and Ismailia.
Distrust and animosity between Islamists and their secular opponents have mired the outcome of Egypt's promised transition to democracy in debates about the legitimacy of the new government and its commitment to the rule of law.
As Wednesday's clashes began, Vice-President Mahmoud Mekki offered a compromise that seemed to go nowhere. He proposed amending the text of the draft constitution to build more support for it before the vote.
''All the political forces objecting to some articles in the constitution are welcome to provide suggestions or concepts about the articles,'' he said, suggesting that through ''calm dialogue'' both sides could agree on amendments that would be approved by the future parliament.
But he did not suggest any means to overcome the lack of trust in the Islamist leaders among the secular opposition, or how to persuade liberals to back down from their vow not to negotiate until Dr Morsi relinquishes the temporary expansion of his powers and cancels the referendum.
Former United Nations diplomat Mohamed ElBaradei was chosen on Wednesday as co-ordinator for the newly unified secular opposition. He urged Dr Morsi and his allies to ''see what is happening in the Egyptian street, the division, the polarisation. This is something that leads us to violence and worse.
''The ball is in his court,'' Mr ElBaradei said at a news conference in which he threatened a general strike or other action to try to stop the referendum. ''Bullying will not yield any results for this country.''
Dr Morsi did not respond to the clashes. His party, founded by the Muslim Brotherhood, said it held Mr ElBaradei and other secular leaders responsible.
The Brotherhood defended the need for Dr Morsi's actions to fight off ''treacherous plots'' against Egypt's nascent democracy. It called any attempt to stop the referendum a ''stumbling block''.
''We are confident that the Egyptian people who made this great revolution that impressed the whole world will not abandon democracy or their revolution,'' the group said, ''and must support the President they chose freely for the first time in history.''
NEW YORK TIMES, AFP