Rival protesters clashed outside the presidential palace in Cairo on Wednesday, as unrest grows over a controversial draft constitution, the BBC reported.
According to the report, petrol bombs were thrown and a number of people were injured, amid reports of shots being fired.
Supporters of President Mohammed Morsi dismantled tents set up outside the presidential palace by Morsi critics.
The clashes erupted after Vice President Mahmoud Mekki said a referendum on the draft will go ahead on December 15 despite the unrest.
He indicated, however, that changes could be made after the vote, saying the "door for dialogue" remained open. Mekki urged critics of the draft document to put their concerns in writing for future discussion.
Critics say the draft was rushed through parliament without proper consultation and that it does not do enough to protect political and religious freedoms and the rights of women.
The draft added to the anger generated by Morsi passing a decree in late November which granted him wide-ranging new powers.
A number of people were injured during the clashes, reported the BBC.
On Wednesday afternoon, supporters of Morsi's Muslim Brotherhood movement rallied outside the presidential palace, where the mainly secular opponents of the president were already staging a protest.
The pro-Morsi group chanted "The people want to cleanse the square" and "Morsi has legitimacy", according to a report by AFP.
Stones and petrol bombs were thrown, and Morsi supporters dismantled some of the tents set up by their opponents, said the report.
There were also reports of gunfire. Witnesses reported seeing a number of wounded people.
AFP said the anti-Morsi group had fled the area.
In a joint news conference, Mohamed ElBaradei, Amr Moussa and other leading figures of the Egyptian opposition said they held Morsi fully responsible for the violence.
"Our opinion was, and still is, that we are ready for dialogue if the constitutional decree is cancelled ... and the referendum on this constitution is postponed," said ElBaradei, according to the BBC.
"The revolution did not happen for this. It happened for freedom, democracy and human dignity. Morsi must listen to the people, whose voice is loud and clear. There is no legitimacy in excluding the majority of the people. There is no legitimacy in enabling one group to dominate Egypt," he said.
Three of Morsi's advisers resigned on Wednesday in an apparent protest. Three others had done so last week.
Morsi reportedly returned to his palace Wednesday morning after violent protesters left the area.
At least 100,000 protesters clashed with police in Tahrir Square and around the presidential palace walls on Tuesday night. Security personnel were unable to keep them at bay with tear gas.