Protesters have broken through a barbed wire barricade outside the presidential palace in the Egyptian capital Cairo.
Thousands of demonstrators had gathered outside the palace following a night of clashes between supporters and opponents of President Mohamed Morsi on Thursday.
After forcing their way through, some protesters climbed onto army tanks and began waving flags, while others reportedly sprayed graffiti on palace walls.
Troops of the Republic Guard moved to the front gate to secure the main entrance to the palace.
Earlier, the main opposition group in Egypt said it would not take part in talks with the country's president aimed at ending unrest.
Ahmed Said, one of the leading members of the National Salvation Front, said the coalition had rejected Mr Morsi's offer of a meeting to discuss how Egypt should move forward after a referendum on a new constitution set for December 15.
Prominent reformist Mohamed ElBaradei also urged politicians to shun the talks, while the state news agency reported that the liberal Wafd party said it would not take part. Both are members of the Front.
The call for talks came amid the worst violence seen in the country since last year's revolution.
Opponents of Mr Morsi have taken to the streets to protest against a decree by Mr Morsi on November 22, giving himself extra powers and protecting himself from judicial review.
At least six people were killed and almost 700 injured in clashes around the palace on Wednesday.
US President Barack Obama called Mr Morsi on Thursday to express his "deep concern" about 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 the start of expatriate voting in the constitutional referendum, the state news agency reported.
Voting was due to begin on Saturday but will now start on Wednesday.
The committee did not say whether the delay would affect the date of the referendum.