Russia has proposed to the U.S.-led coalition that they stage joint air strikes on Syrian rebels, including militant Islamist group Nusra Front, who are not observing a ceasefire, but the US responded coolly on Friday.
A rebel onslaught on the town of Khan Touman near Aleppo last week delivered one of the biggest battlefield setbacks yet to the coalition of foreign Shi'ite fighters waging war on behalf of Syrian President Bashar al Assad.
Russia's defence ministry said a "regime of calm" truce in the northern Syrian city of Aleppo and parts of Latakia province had been extended "for 72 hours beginning at 1 am on Saturday" (2200 GMT on Friday), Syrian state
The Syrian Observatory for Human Rights on Friday reported that insurgent groups captured a strategically important village from government forces in fierce fighting south of Aleppo that killed 73 people.
The insurgents, including
Rebels seized a town in southern Syria from groups loyal to Islamic State just a day after fighters captured another town from the hardline militants in a separate insurgent assault in the north, a rebel source and a monitoring group said.
Syrian rebels in the country's northwest said they came under attack from government ground forces at 4 a.m. (0200 GMT) on Saturday in what they called a breach of the cessation of hostilities plan that came into effect at midnight.
The government of Syrian President Bashar Al-Assad and rebel groups accepted a plan for a cessation of hostilities to begin on Saturday and the US warned it would be hard to hold the country together if the fighting did not stop.
Syrian President Bashar al-Assad said on Saturday he was ready for a ceasefire, on condition "terrorists" did not use a lull in fighting to their advantage and that countries backing insurgents halted support for them.
A United Nations envoy halted his attempts to conduct Syrian peace talks on Wednesday after the army, backed by Russian air strikes, advanced against rebel forces north of Aleppo, choking opposition supply lines from Turkey to the city.
Islamic state militants killed dozens of people execution style in attacks on government-held areas in Syria's city of Deir al-Zor on Saturday, a source and a monitoring said.
A source close to the Syrian government side said