Egypt's ruling military on Tuesday discussed the possibility of appointing ex-UN nuclear watchdog chief Mohamed ElBaradei to head a new government after the cabinet's resignation, a military source told AFP.

The ruling Supreme Council of the Armed Forces (SCAF) had invited the country's political forces to crisis talks in a bid to contain deadly clashes raging for the fourth day between police and protesters demanding democratic reforms.

The military source, who attended the talks, said discussions centred on the resignation of Prime Minister Essam Sharaf's cabinet which was tendered on Sunday but has yet to be accepted.

The meeting also discussed the idea of forming a new government headed by ElBaradei or Abdelmoneim Abul Futuh, a presidential hopeful and former member of the powerful Muslim Brotherhood, the source said.

The SCAF is facing its worst crisis yet since it took power when a popular uprising toppled veteran president Hosni Mubarak in February.

Thousands of protesters descended on Cairo's Tahrir Square -- the symbolic heart of the uprising -- ahead of a mass rally called for 1400 GMT to demand the military cede power to a civilian authority.