Supporters of Egyptian president Mohammed Mursi have clashed with rival protesters outside the presidential palace in Cairo as protests escalate over controversial changes in the constitution.
Dozens of demonstrators were injured and there were unconfirmed reports of two people killed after thousands of Mursi's Muslim Brotherhood supporters barged into the square where anti-government supporters were staging a rally.
There were also claims that three of Mursi's advisers had resigned.
Demonstrators from the opposing factions threw Molotov cocktails at each other. Gunshots were also heard, al-Arabiya reported, before police intervened to separate the groups.
Turmoil has been ongoing in Egypt since late November after Mursi granted himself enlarged powers, including immunity from the judiciary and the irrevocability of his decisions, until a new constitution was drafted.
Mursi said the move was necessary to safeguard the revolution and prevent Hosni Mubarak-era judges in the supreme court overturning the elected parliament before the new constitution was approved.
Mursi's constitutional draft was written after a marathon 21-hour negotiation session and will be put to a referendum on December 15.
Mursi said he would relinquish the powers that granted him the nickname of new pharaoh of Egypt after the referendum.
Critics said the new constitution maintains the sharia law principles already in force under Mubarak and restricts basic rights.
"[Mursi] put to referendum a draft constitution that undermines basic freedoms & violates universal values.The struggle will continue," tweeted Egyptian Nobel Peace Prize laureate Mohamed ElBaradei.
Vice-president Mahmoud Mekki said the referendum would go ahead despite growing unrest and violence - but it was also open to amendment.
"[The referendum] will go ahead on time," Mekki said.
"The demands of opposition protesters must be respected. I am completely confident that if not in the coming hours, then in the next few days we will reach a breakthrough in the crisis and consensus."