Beginning on Friday, the demonstration in Tahrir Square was initially led by Islamists, angry at a bid by the army-backed cabinet to lay down principles for a new constitution that would have kept the army out of the control of a future civilian government. 

But since Saturday, the protest has largely been carried out by the same youthful activists who galvanised Egyptians to bring down Mubarak, putting national pride before religion.

They are demanding Egypt’s ruling generals hand over power.

The clashes between government forces and protesters feautre some of the worst violence since the overthrow of Hosni Mubarak. In one battle, the police attacked a makeshift field hospital, while protesters broke up pavements to hurl the chunks of concrete at police.

The demonstrators showed media spent shotgun cartridges and bullet casings, although police denied using live rounds.

Security forces burnt down banners, and Internet clips, which could not be independently verified, showed police pulling protestors by the hair,  beating them with sticks,  and, in one case, dumping what appeared to be a corpse on piles of rubbish.

“There is clearly no going back as you can see this violence cannot be swept under the table,” said protestor Essam Gouda.

“We aim to control the entry points to the square so that security doesn’t block protesters from entering.”

Tahrir Square was the rallying point for protesters in Cairo when an 18-day uprising toppled Mubarak from three decades of power in February.

With just a week before voting in Egypt’s first free parliamentary election in decades, the confrontations have raised concerns about how smooth voting will be.

Egyptians elect a new parliament in a staggered vote that starts on November 28, but even when the assembly is picked, presidential powers remain with the army until a presidential poll, which may not happen until late 2012 or early 2013. Protesters want a much swifter transition.