A Western-backed coalition of Syria's opposition to President Bashar al-Assad says it is ready to work with the US to fight the Islamic State.
Syria's governement says a presidential election will take place on June 3, but Western leaders say the vote is a "parody of democracy".
The war has forced some 50 000 Palestinians to flee Syria, a country where they had enjoyed some of the most favourable treatment in the Arab world.
Families have tried to identify hundreds of mutilated bodies piled in a Cairo mosque a day after they were shot dead by the security forces.
Russia's President Vladimir Putin has said that Egypt risks slipping into civil war following the military overthrow of president Mohamed Morsi.
Morsi supporters are planning a protest against the ousting of Egypt's first democratically elected president.
The UN has been left to ponder the validity of the ouster of Egypt's President Mohamed Morsi, while the West considers placing sanctions on aid.
Twelve people were killed when an explosion rocked a government-held district of the disputed Syrian city of Aleppo, a monitoring group said.
Libyan interim government forces swarmed into Muammar Gaddafi's home town of Sirte on Saturday but encountered heavy sniper fire.
Libya's interim rulers said they had captured one of Muammar Gaddafi's last strongholds in the Sahara desert, finding a stock of chemical weapons.