Protesters calling for Egypt's military to hand over power have beaten back a new raid by security forces to evict them from Cairo's Tahrir Square after more than 48 hours of violence in the heart of the Egyptian capital.

Security forces fired tear gas and attacked a makeshift field hospital on Monday morning, while protesters broke up pavements to hurl chunks of concrete at police.

Al Jazeera's Mike Hanna, reporting from Tahrir Square, said: "Throughout the morning plumes of tear gas are rising over houses. There are sporadic clashes happening around the outskirts of the square."

The violence has been some of the worst since the overthrow of Hosni Mubarak in February when Tahrir Square was the major rallying point for protesters during the 18-day uprising that ended the former president's three decades of power.

Egypt's health ministry said at least 22 people have been killed and 1,500 wounded in clashes between government forces and protesters in Cairo and other cities since Saturday, raising concerns over parliamentary elections due to begin later this month.

On Sunday, a press conference planned for Monday to detail how the election process would proceed was postponed with no new date set.

Several political parties and individual candidates said they were suspending their electoral campaign, raising concerns over whether the vote will go ahead or be postponed.

Back-and-forth battles

Police backed by army officers fired tear gas and charged demonstrators in the square as darkness fell on Sunday night, temporarily sending protesters fleeing.

Security forces burned down banners and video footage posted on the internet, which could not be independently verified, showed police beating protesters with sticks, pulling them by the hair and, in one case, dumping what appeared to be a corpse on piles of rubbish.

Demonstrators swiftly regrouped in side streets and returned to take control of the square during the night. Police tried again to retake Tahrir after dawn.

A makeshift field clinic was set up as injured protesters streamed in suffering from ammunition wounds from rubber-coated steel bullets, birdshots, and tear gas.

Late on Sunday, a deal was reached between Imam Mazhir Shahin, who led last Friday's prayers, and security officials allowing protesters to remain in the centre of the square as long as they didn't move to government buildings around the perimeter of the plaza.

Even so, clashes on also took place near Cairo's interior ministry and in major cities throughout Egypt, including the major population centres of Alexandria and Suez.

Protesters clashed with police on the streets of Alexandria late on Sunday and in the city's neighbourhood of Smouha protesters pelted police with stones. In response, police fired canisters of teargas in a bid to disperse angry crowds.

"The confrontations that we saw here overnight were very intense, with the people on the street telling us there is no doubt now that the military has shown its true colours," Al Jazeera's Rawya Rageh said, reporting from Alexandria.

Swift transition

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

The Supreme Council of the Armed Forces (SCAF), Egypt's ruling council, repeated its commitment to its "roadmap" for transition and expressed "sorrow" over the situation.

"We are all insisting on having the election on time; the government, parties and the Supreme Council of the Armed
Forces," Mohamed Hegazy, a cabinet spokesman, told the Reuters news agency.

Major General Said Abbas, the deputy head of the central military, told protesters and press near Tahrir Square that people have the right to protest and the SCAF is committed to hand over authority.

The security crackdown on protesters elicited condemnation from parties across the political spectrum; from Mohamed ElBaradei, a presidential hopeful and head of the National Association for Change, to the Muslim Brotherhood's Freedom and Justice Party.

There have also been repeated calls for the formation of the National Salvation Council which would take over from the military.

ElBaradei said on a late-night talk show: "The prime responsibility for the situation of the country is the SCAF, who [has] admitted they cannot run the country.”

Abdel Moneim Aboul Foutouh, a longtime Muslim Brotherhood member, who was also on the talk show blamed the SCAF for maintaining an ambiguous political position and called on the military council to publish a clear plan for a power handover.