CAIRO - Egypt's army has plans to push Mohamed Mursi aside and suspend the constitution after an all but impossible ultimatum it has given the Islamist president expires in less than 24 hours, military sources told Reuters on Tuesday.

Supporters of President Mohamed Mursi wave to a military helicopter passing over them during a protest in Alexandria to counter anti-Mursi protests elsewhere in Alexandria, July 2, 2013. [Photo/Agencies]

Condemning a coup against their first freely elected leader, tens of thousands of Mursi's Muslim Brotherhood supporters took to the streets, clashing with opponents in several towns. But they appeared to be dwarfed by anti-government protesters who turned out in their hundreds of thousands across the nation.

Troops were on alert after warnings of a potential civil war. Seven people died in fighting in Cairo suburbs and hundreds were wounded in the provinces.

Mursi defied a demand by the armed forces chief on Monday that he agree to share power with his opponents within 48 hours or have the generals take charge. Calling the army statement misleading and divisive, he said he would stick to his own plan.

But time has all but run out for Mursi, as liberal leaders are refusing to talk to him. Opponents have been dancing in the streets since the intervention by General Abdel Fattah al-Sisi.

Military sources told Reuters that, assuming the politicians failed to end a year of deadlock under Mursi before Wednesday's 5 p.m. (1500 GMT) deadline, the generals had their own draft program ready to implement - though it could be fine-tuned in consultation with willing political parties.

Under the roadmap, the military would install an interim council, composed mainly of civilians from different political groups and experienced technocrats, to run the country until an amended constitution was drafted within months.

That would be followed by a new presidential election, but parliamentary polls would be delayed until strict conditions for selecting candidates were in force, the sources said.

They would not say how the military intended to deal with Mursi if he refused to go quietly. One power he might seek to exercise would be to call a referendum on continuing his term.

Some of his Islamist supporters have vowed to defend what they see as the legitimate, democratic order, even if it means dying as martyrs. And some have a history of armed struggle against the state.