Tens of thousands have packed Tahrir Square to protest a power grab by Mohamed Morsi, piling pressure on Egypt's Islamist president as he faces his most divisive crisis since taking power in June.
The huge turnout in the iconic square in the heart of Cairo, as well as in the Mediterranean city of Alexandria and most of Egypt's 27 provinces on Tuesday, marked the largest mobilisation yet against the president.
Elsewhere in the country, protesters enraged by Morsi's decision to grant himself sweeping powers attacked three regional headquarters belonging to the president's Muslim Brotherhood movement, a security official said.
Egyptian protesters wave their national flag duirng a protest in Cairo's Tahrir Square against President Mohamed Morsi's decree granting himself broad powers. Tens of thousands have packed Tahrir Square to protest a power grab by Morsi, piling pressure on Egypt's Islamist president as he faces his most divisive crisis since taking power in June.
In Tahrir, protesters who had voted for Morsi in the election joined forces with die-hard opponents of the Islamist.
"I'm here to protest Morsi's autocratic decisions," said Mohammed Rashwan, an engineering graduate who voted for Morsi in the country's first presidential election since a popular uprising toppled Hosni Mubarak last year.
Three people have died in clashes since Morsi decreed his new powers.
A rival rally in Cairo by the Muslim Brotherhood on Tuesday in support of the president was called off to "avoid potential unrest" but that has done little to abate the split between Morsi's supporters and foes.
Meanwhile US officials said Washington was closely following the drama unfolding in Egypt, with a warning that Cairo could put vast amounts of international aid at stake if it veers back off the democratic course.
The situation was evolving, State Department spokeswoman Victoria Nuland said.
"I think we don't yet know what the outcome of those are going to be. But that's a far cry from an autocrat just saying, my way or the highway," she said.
Despite her carefully worded statement on Tuesday, the US embassy in Cairo seemed to suggest that Egypt was indeed on the path to a new dictatorship.
"The Egyptian people made clear in the January 25th revolution that they have had enough of dictatorship," the embassy tweeted in a message on its Twitter account.
Nuland stressed that "we want to see Egypt continuing on a reform path to ensure that any money forthcoming from the IMF truly supports a stabilisation and a revitalisation of a dynamic economy based on market principles."
The International Monetary Fund on Tuesday said Egypt can still get its $4.8 billion loan, agreed last week, despite the turmoil as long as there is "no major change" in its reform commitments.
The Egyptian protesters are angry at the decree that Morsi announced last Thursday allowing him to "issue any decision or law that is final and not subject to appeal", which effectively placed him beyond judicial oversight.
The decree put him on a collision course with the judiciary and consolidated the long-divided opposition which accuses him of taking on dictatorial powers.
The demonstrations come a day after Morsi stuck by his decree after a meeting with the country's top judges aimed at defusing the crisis.
Clashes between police and protesting youths erupt near Cairo's Tahrir Square, ahead of a mass rally against a decree by President Mohamed Morsi granting himself broad powers. Marches are planned from across the capital into Tahrir, the epicentre of protests that toppled Hosni Mubarak last year, where the numbers are expected to swell after the end of the work day. Duration: 01:00
There has been "no change to the constitutional declaration", presidential spokesman Yasser Ali told reporters at the end of the meeting.
But he added Morsi sought to clarify that any irrevocable decisions apply only to issues related "to his sovereign powers" and stressed the temporary nature of the decree.
The head of the Freedom and Justice Party (FJP) -- the Brotherhood's political arm -- said the meeting between Morsi and the judges had been "fruitful".
But judges said the crisis was not over.
"The meeting failed," Judge Abdel Rahman Bahlul, who attended the talks, told the independent daily Al-Masry Al-Youm.
"We cannot say this is the end of the crisis between the judiciary and the presidency," another judge who attended the talks, Judge Ahmed Abdel Rahman, told the paper.
A judicial source told AFP that even if immunity were limited to sovereign powers, "which appears to be a compromise, there are still concerns that the text itself remains unchanged".
The decree bars the courts from dissolving a controversial panel that is drafting a new constitution. Liberals, leftists and church leaders have already walked out of the Islamist-dominated panel charging that it fails to represent all Egyptians.