Tens of thousands of protesters have demonstrated overnight outside Egypt's presidential palace, calling on President Mohamed Morsi to step down.
The peaceful night-time demonstration followed a tense day in which Mr Morsi's opponents broke through a barbed-wire security barricade outside the palace, climbing on army tanks and waving flags.
The country's powerful military has urged political forces to solve the crisis through dialogue, saying in its first statement since the protests erupted that it would prevent violence.
"The armed forces affirm that dialogue is the best and only way to reach consensus," it said on Saturday. "The opposite of that will bring us to a dark tunnel ... which we will not allow."
The protesters say a new decree gives Mr Morsi pharaoh-like powers Some protesters overnight chanted "Leave! Leave!" to Mr Morsi, who is backed by the Muslim Brotherhood, while others daubed walls with graffiti and cartoons.
One caricature portrayed Mr Morsi with blood on his mouth, another depicted him as a pharaoh – a reference to a recent decree that expanded his powers and barred court challenges to his decisions.
After the night of protests, the streets of Cairo were calm.
A referendum on a new draft constitution opposed by liberals is set for December 15, and Mr Morsi has called for talks with the opposition to discuss how Egypt should move forward after the vote.
Amid the protests, Mr Morsi's deputy has raised the possibility that the referendum might be delayed.
But major opposition leaders have rejected Mr Morsi's call dialogue.
Mohammed El Baradei, a Nobel peace laureate and opposition figure, dismissed the offer as "arm-twisting and imposition of a fait accompli".
Soldiers guard the presidential palace after the overnight protest The unrest is the worst since last year's revolution, which toppled ex-president Hosni Mubarak, and the subsequent vote that made Mr Morsi the country's first freely elected leader.
At least six people have been killed and almost 700 injured in clashes around the palace.
"We will stay here for as long as it takes and will continue to organise protests elsewhere until President Morsi cancels his constitutional decree and postpones the referendum," said Ahmed Essam, 28, a computer engineer who took part in the overnight protest.
The upheaval in the most populous Arab nation worries the West, in particular the United States, which has given it billions of dollars in military and other aid since Egypt made peace with Israel in 1979.
US President Barack Obama called Mr Morsi on Thursday to express his "deep concern" over the deaths and injuries.
He welcomed the offer of talks but warned they should be entered into "without preconditions", a White House spokesman said.
Meanwhile, Egypt's election committee has postponed to Wednesday the start of expatriate voting in the constitutional referendum, originally planned for Saturday.
The committee did not say whether the delay would affect the date of the referendum.
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