CAIRO (AFP) - Several hundred thousand Egyptians massed Tuesday for the biggest outpouring of anger yet in their drive to oust President Hosni Mubarak, on day eight of a revolt in which an estimated 300 have died.

Demonstrators flooded Cairo's Tahrir square protest epicentre from early morning for a "march of a million" set for the capital and second city Alexandria as foreign governments scrambled to evacuate their nationals.

The opposition said it would not negotiate with Mubarak, with Mohamed ElBaradei, who is emerging as a leader of anti-regime protests, telling Al-Arabiya satellite channel that Mubarak should go by Friday.

A committee of opposition groups, which includes ElBaradei and the powerful Muslim Brotherhood, also pledged there would be no negotiations with the regime until Mubarak "leaves," a statement said.

Many protesters spent the night on the square in tents or just sleeping on the grass, unbowed by the presence of troops and tanks.

The army, which has said it will not shoot at protesters, checked IDs and searched protesters before allowing them into the square. Civilians then checked IDs again, fearing plain-clothes police acting as agents provocateurs.

"I will stay here till I die," said a defiant Osama Allam.

"If I die now my whole family will be proud of me. This is what the Egyptian people need," said the 43-year-old lawyer, an effigy of veteran Mubarak hanging from nearby traffic lights, "Off with your head" daubed on his face.

"This revolution does not belong to any political party, Muslim group, any group, just the poor Egyptian people," said one elderly man, declining to give his name as protesters carried Mubarak's mock coffin past him shoulder high.

"Freedom or death!" shouted Tarek Shabassi. "I'm ready to stay here 10, 20, 30 years. Dying means nothing to me because I've been dead for 30 years, since Mubarak came to power."

UN High Commissioner for Human Rights Navi Pillay said on Tuesday that according to unconfirmed reports, a total of 300 people have died in the anti-government unrest.

"Casualties have been mounting on a daily basis, with unconfirmed reports suggesting as many as 300 people may have been killed so far, more than 3,000 injured and hundreds arrested," she said in a statement released in Geneva.

A second million-strong march was planned for the Mediterranean port city of Alexandria on Tuesday, as authorities cancelled train services and blocked main access roads.

An AFP correspondent on the main Cairo-Alexandria road said troops were stopping vehicles entering the capital. When motorists argued, one soldier cocked his assault rifle and told the angry civilians to step back.

But vehicles could still head in the other direction towards Alexandria, while regularly being stopped and searched by the army.

In a bid to defuse the crisis, Mubarak announced a new cabinet that saw the demise of a widely feared interior minister, and his newly appointed vice president offered talks with the opposition.

But protest organisers denounced the moves as too little too late and announced an indefinite general strike, upping the pressure on Mubarak, in power for 30 years.

It was difficult to assess the impact of the strike call, however, with many businesses closed over security concerns or because people were demonstrating.

While the police reaction to the strike and marches remains unknown, the army stated clearly it would not confront the demonstrators.

"To the great people of Egypt, your armed forces, acknowledging the legitimate rights of the people," stress that "they have not and will not use force against the Egyptian people," the military said in a statement.

Faced with the biggest protests of his presidency, an increasingly embattled Mubarak has appointed his first-ever vice president and a new premier in a desperate attempt to cling to power.

A new cabinet unveiled on Monday did little to placate the protesters, but the departure of interior minister Habib al-Adly, whose notorious security forces have been accused of systematic human rights violations, was welcomed.

"We will accept no change other than Mubarak's departure," said one protester who asked not to be identified.

Vice President Omar Suleiman said Mubarak had tasked him "with opening immediate talks with the political forces to begin a dialogue around all the issues concerning constitutional and legislative reforms."

But with the opposition groups saying they would not do so until Mubarak goes, there looked little likelihood of an early negotiated end to the uprising.

Nobel peace laureate ElBaradei told Al-Arabiya satellite channel that Mubarak should go by Friday.

"What I have heard (from protesters) is that they want this to end, if not today (Tuesday), then by Friday maximum," he said.

"I hope President Mubarak goes before this and leaves the country after 30 years of rule... I don't think he wants to see more blood."

Earlier, he told Britain's Independent newspaper that Mubarak should leave "if he wants to save his skin".

"When a regime withdraws the police entirely from the streets of Cairo, when thugs are part of the secret police, trying to give the impression that without Mubarak the country will go into chaos, this is a criminal act.

Somebody has to be accountable," he said.

"And now, as you can hear in the streets, people are not saying Mubarak should go, they are now saying he should be put on trial. If he wants to save his skin, he better leave."

Washington, a key ally of Egypt, has urged Mubarak to do more to defuse the crisis, with President Barack Obama calling for "an orderly transition to a government that is responsive to the aspirations of the Egyptian people."

The New York Times reported on Tuesday that Frank Wisner, a former U.S. ambassador to Egypt, had been sent to meet Mubarak directly, but that officials would not say whether Wisner would urge him to leave office.

Amid the chaos, several foreign governments said they would evacuate their nationals, and Washington authorised the departure of U.S. embassy families.

International Monetary Fund chief Dominique Strauss-Kahn said in Singapore the IMF was ready to help Egypt, where rising food prices could have "potentially devastating consequences."

He declined to comment on the turmoil, "but clearly the situation in Egypt is the kind of situation that could have been expected not only in Egypt, when you see the problem created by the high level of unemployment."

Standard and Poors, meanwhile, lowered its debt ratings for Egypt a day after a similar move by Moody's, saying ongoing instability "will hamper Egypt's economic growth and adversely affect its public finances."