Video | Violence between pro-Mubarak and anti-regime protesters escalates

Al Jazeera correspondents, reporting from the scene, said that more than 500 people had been injured in Wednesday's clashes that are continuing to rage and the number seems to be rising fast.

Earlier, witnesses said the military allowed thousands of pro-Mubarak supporters, armed with sticks and knives, to enter the square. Opposition groups said Mubarak had sent in thugs to suppress anti-government protests. Two Molotov cocktails have been thrown into the grounds of the Egyptian Museum, it is being reported

Many of the Egyptian police force is openly in the Pro-Mubarak camp - something that the opposing sides have been maintaining.

Al Jazeera correspondents also reporting that the army seemed to be standing by and facilitating the clashes. Latest reports suggest that the centre of the square is still in control of the protesters, despite the pro-Mubarak supporters gaining ground.

Witnesses also said that pro-Mubarak supporters were dragging away protesters they had managed to grab and handing them over to security forces.

Salma Eltarzi, an anti-government protester, told Al Jazeera there were hundreds of wounded people. "There are no ambulances in sight, and all we are using is Dettol," she said. "We are all so scared."

Aisha Hussein, a nurse, said dozens of people were being treated at a makeshift clinic in a mosque near the square. She described a scene of "absolute mayhem", as protesters first began to flood into the clinic.

Al Jazeera's correspondent added that several a group of pro-government protesters took over army vehicles. They also took control of a nearby building and used the rooftop to throw concrete blocks, stones, and other objects.

Soldiers surrounding the square took cover from flying stones, and the windows of at least one army truck were broken. Some troops stood on tanks and appealed for calm but did not otherwise intervene.

Al Jazeera's Jane Dutton, also in Cairo, said that security guards have also been seen amongst the pro-Mubarak supporters, and it may be a precursor to the feared riot police arriving on the scene. Dutton added that a journalist with the Al-Arabiya channel was stabbed during the clashes.

Fighting took place around army tanks deployed around the square, with stones bouncing off the armoured vehicles. Soldiers did not intervene. Several groups were involved in fist fights, and some were using clubs.  The opposition also said many among the pro-Mubarak crowd were policemen in plain clothes.

"Members of security forces dressed in plain clothes and a number of thugs have stormed Tahrir Square," three opposition groups said in a statement.

International Reactions

The violence drew condemnation from British Prime Minister David Cameron.

"If it turns out that the regime in any way has sponsored or tolerated this violence, that is completely unacceptable," he said after meeting UN Secretary General Ban Ki-moon in London.

Mr Ban said: "Any attack against the peaceful demonstrators is unacceptable and I strongly condemn it."

In Washington, the state department reiterated a call for all sides to show restraint.

In its earlier statement, Egypt's army called for demonstrators to return to their homes.

"Your message has arrived, your demands became known... you are capable of bringing normal life to Egypt," said a spokesman in a message broadcast on state television.

In Tuesday night's speech, Mubarak had promised to leave at the next polls, and pledged constitutional reform, saying he would devote his remaining time in power to ensuring a peaceful transition to his successor.

US President Barack Obama responded by saying an orderly transition "must begin now", while Turkey's PM Recep Tayyip Erdogan said Mr Mubarak should take a "different step".

Opposition leader Mohamed El Baradei dismissed Mubarak's move as "a trick" to stay in power, and Tahrir Square protesters have vowed to continue their demonstrations until Mubarak quits.

Abdelhalim Kandil, leader of Egypt's Kifaya (Enough) opposition movement, said Mubarak's offer not to serve a sixth term was not enough.