Syria's army ambushed Islamist fighters in the Qalamoun mountains north of the capital Damascus on Friday, leaving as many as 60 people dead, the Syrian Observatory for Human Rights said.
The attack happened between the Christian town of Maaloula and the town of Yabroud, where government forces and rebels are fighting, said the Observatory, a British-based, pro-opposition monitoring group with sources across Syria.
Syria's civil war between forces loyal to Syrian President Bashar Assad and mostly Sunni Muslim rebels fighting to topple him has killed more than 100,000 people since March 2011.
Syrian state television showed footage of dozens of bodies lying in a mountainous area, with machine guns and rocket-propelled grenades next to them.
"There were about 400 of us including Saudis, Chechens and other nationalities," a badly wounded fighter who was lying on the ground told a state television reporter who was asking him about numbers and nationalities.
The fighter said he belonged to Liwa al-Islam, a Salafist jihadi group that is one of the biggest and best organized rebel units fighting to topple Assad.
The government television reporter said the army tracked the fighters overnight and ambushed them on their way to the town of Jayrud, 20 kilometers (15 miles) southeast of Yabroud.
It was not possible to verify the report independently due to restrictions on the media in Syria.
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