Cairo, Jan 31 (Reuters): President Hosni Mubarak, clinging on despite mass popular demands for an end to his 30-year rule, met on Sunday with the generals who may hold the keys to Egypt's future, but in Cairo protesters defied a curfew.

As his key ally the United States called for an "orderly transition", Mubarak's desparate opponents, including the banned Muslim Brotherhood, rallied behind retired international diplomat Mohamed ElBaradei to lead possible talks with the army on organising a handover of power to a national unity coalition.

"I ask of your patience, change is coming in the next few days," Baradei told thousands of demonstrators on Cairo's Tahrir Square after dark. "You have taken back your rights and what we have begun, cannot go back."

He added: "We have one main demand -- the end of the regime and the beginning of a new stage, a new Egypt."

"The people want the regime to fall!" thousands chanted as troops looked on patiently from their U.S.-built battle tanks.

Baradei, 68, won a Nobel peace prize as head of the United Nations' nuclear body. Though little known to many Egyptians, he had hoped to run in a presidential election in September.

U.S. Secretary of State Hillary Clinton told Fox News: "We want to see an orderly transition so that no one fills a void.

"We also don't want to see some takeover that would lead not to democracy but to oppression and the end of the aspirations of the Egyptian people."

For a week, since Egyptians inspired by the overthrow of the ageing strongman in Tunisia began a push for change, it has been unclear who might emerge as an alternative to Mubarak and, more widely, to the military class which has run Egypt since 1952.

MUSLIM BROTHERHOOD

A senior figure in the Muslim Brotherhood, the banned Islamist group that has long seemed the strongest single force against Mubarak, said it backed ElBaradei as negotiator.

The Brotherhood has stayed in the background although several of its senior officials have been rounded up. The government has accused it of planning to exploit the protests.

Some of its leaders walked free from jails on Sunday.

As many as 10,000 people protested in Tahrir Square, a rallying point in the centre of Cairo, to express anger at poverty, repression, unemployment and corruption -- themes that are rumbling across the Arab world after first Tunisia and now the most populous Arab state Egypt have been plunged in unrest.

 As the curfew started and was ignored, warplanes and helicopters flew over the square. By late afternoon more army trucks appeared in a show of military force but no one moved.

"Hosni Mubarak, Omar Suleiman, both of you are agents of the Americans," shouted protesters, referring to the appointment on Saturday of intelligence chief Suleiman as vice president, the first time Mubarak has appointed a deputy in 30 years of office.

It was the position Mubarak, 82, held before he become president and many saw the appointment as ending his son Gamal's long-predicted ambitions to take over and as an attempt to reshape the administration to placate reformists.

Mubarak held talks with Suleiman, Defence Minister Mohamed Hussein Tantawi, Chief of Staff Sami al-Anan and others.

Clearly those in Tahrir Square did not wish to see Mubarak's ruling structure replaced by a military line-up featuring his closest associates. "Mubarak, Mubarak, the plane awaits," they said. There was also a big protest in Alexandria.

SHOCKWAVES AROUND MIDDLE EAST

The turmoil, in which more than 100 people have died, has sent shock waves through the Middle East where other autocratic rulers may face similar challenges, and unsettled financial markets around the globe as well as Egypt's allies in the West.

In Tunisia, the detonator of the regional movement, an exiled Islamist leader was welcomed home by thousands on Sunday. In Sudan, Egypt's southern neighbour, police beat and arrested students taking part in anti-government protests in Khartoum.

In Egypt, the military response to the crisis has been ambivalent. Troops now guard key buildings after police lost control of the streets, but have neglected to enforce a curfew, often fraternising with protesters rather than confronting them.

It remains to be seen if the armed forces will keep Mubarak in power, or decide he is a liability to Egypt's national interests, and their own. It was also unclear if Mubarak had decided to talk with the generals or if he was summoned by them.

It was Tunisian generals who persuaded former President Zine al-Abidine Ben Ali to flee last month after weeks of protests.

In Suez, on the canal, one senior local officer, Brigadier Atef Said said his troops would give protesters a free voice:

"We will allow protests in the coming days," he told Reuters. "Everyone has the right to voice their opinion."

The crisis deepened on Sunday after police had disappeared from the streets. Egyptians faced lawlessness on the streets with security forces and citizens trying to stop looters.

Through the night into Sunday, Cairo residents armed with clubs, chains and knives formed vigilante groups to guard neighbourhoods from marauders after the unpopular police force withdrew following the deadly clashes with protesters.