Huge crowds have occupied the main square in the Egyptian capital, Cairo, to reinforce their demand for the resignation of President Hosni Mubarak.
The tens of thousands of protesters attending the "day of departure" rally in Tahrir Square waved flags and chanted "Leave! Leave! Leave!"
Soldiers have been guarding the area to limit disruption by Mubarak supporters.
Mr Mubarak has said he is "fed up" with being in power, but that he does not want to resign as it will cause chaos.
Meanwhile, speaking in Washington, US President Barack Obama called for an "orderly transition that begins right now" in Egypt.
Mr Obama said the "entire world is watching" and urged Mr Mubarak to "make the right decision".
Mr Mubarak told ABC News on Thursday that the banned Islamist opposition group, the Muslim Brotherhood, would fill a power vacuum left by his absence.
He also denied that his administration was behind the violence of recent days, and that his son Gamal intended to run for president.
Opposition leader Mohamed ElBaradei took issue with the president's remarks, saying: "We as a people are fed up as well, it is not only him."
"The idea that there would be chaos is symptomatic of a dictatorship. He thinks if he leaves power the whole country will fall apart."
And White House spokesman Robert Gibbs also rejected the argument that there might be chaos if Mr Mubarak stepped down now.
"There are concrete actions that he can take... towards moving down the path of real change that can lessen instability and can ensure that we do not descend into the chaos that he describes," he told reporters.
"The government, the president and the vice-president need to sit down with a coalition that constitutes a broad cross-section of Egyptian society... Until that happens, my guess is that the people you see on TV aren't going anywhere," he added.
A senior member of the Muslim Brotherhood, Issam al-Aryan, meanwhile denied that his group had eyes on the presidency, telling the BBC that it would prefer the opposition to nominate a consensus candidate.
"We want a civil state, based on Islamic principles. A democratic state, with a parliamentary system, with freedom to form parties, press freedom, and an independent and fair judiciary," he added.
Tens of thousands of people - including large numbers of women and children - gathered in Tahrir Square on Friday for an eleventh day of protest.
Those attending the "day of departure" had to queue for hours on the main bridge over the Nile so they could pass through checkpoints staffed by soldiers and anti-government demonstrators.
They were set up to prevent Mubarak supporters entering and triggering further violent clashes.
Egypt's health ministry says eight people were killed and more than 800 injured in the clashes in Cairo in recent days. The UN believes more than 300 have died across Egypt since the protests began on 25 January, with about 4,000 hurt.
At noon, thousands of the protesters paused to take part in Friday prayers. One cleric praised the "revolution of the young" and declared: "We want the head of the regime removed."
As soon as the prayers finished, the protesters renewed their chants of "Leave", and began singing patriotic songs and waving flags.
At one point, Defence Minister General Mohammed Hussein Tantawi and other military leaders visited the square and spoke to soldiers manning a cordon, as well as some of the demonstrators.
The secretary-general of the Arab League, Amr Moussa, also made an appearance. Some people shouted "We want you as president".
Asked earlier by French radio if he would consider taking a role in any transitional government or run for office, he replied: "Why say no?"
There were reports of minor clashes between pro- and anti-government demonstrators around the square on Friday, but the main rally by Mubarak supporters took place in the Mohandiseen district.
Meanwhile, thousands of anti-government protesters again gathered outside the main mosque in Egypt's second city, Alexandria.
The BBC's Wyre Davies said there were visibly more soldiers and tanks in strategic positions across the city, while armed police in uniform and plain clothes were seen near the main square.
Our correspondent saw protesters beat one secret policeman, who was then bundled into a car and taken away.
There have reportedly also been anti-government protests involving tens of thousands of people in the towns of Suez, Port Said, Rafah, Ismailiya, Zagazig, al-Mahalla al-Kubra, Aswan and Asyut.
Vice-President Omar Suleiman - a close ally of Mr Mubarak who has been director of the powerful General Intelligence Department since 1993 - has appealed for calm and urged the protesters to accept the president's pledge on Monday that he would not stand for re-election in September.
But there are reports that the White House has been in talks with Mr Suleiman about how Egypt can begin making a "peaceful, orderly and meaningful transition, with credible, inclusive negotiations".
The New York Times suggested that among the proposals was a plan for Mr Mubarak to resign immediately and hand power to a military-backed three-man constitutional council headed by Mr Suleiman.
The BBC's Mark Mardell in Washington says other reports suggest the US plan has already been rebuffed in Egypt, and that the administration has been surprised by the attitude of the military and Mr Suleiman.
After a meeting on Friday, European Union leaders expressed their concern at the deteriorating situation, and called the Egyptian authorities to meet the aspirations of the people with "reform not repression" and begin an orderly transition now.
Egyptian Prime Minister Ahmed Shafiq told BBC Arabic that 80% of the protesters' demands had been met, and that Mr Mubarak's decision not to seek re-election was tantamount to the "departure" they were demanding.
"In effect, the president has stepped down already," he said. "We need him during these next nine months."
He separately told al-Arabiya that it was unlikely Mr Mubarak would hand over power to Mr Suleiman, because the president was needed "for legislative reasons". The ruling NDP party has said the vice-president will not be able to amend the constitution or dissolve parliament.
Meanwhile, the government has imposed a travel ban and asset freeze on the former Trade Minister, Rashid Mohammed Rashid Hussein, pending an inquiry into the alleged misuse of public funds. He told BBC Arabic that he was bewildered by the decision.
And Mohammed Rifaa Tahtawi, the spokesman of al-Azhar - the Cairo-based institution which is seen as the highest authority in Sunni Islam - has resigned. He told reporters: "I am participating in the protests and I have issued statements that support the revolutionists as far as they go."