At least 34 foreign jihadists from the Islamic State of Iraq and the Levant and an ally were killed after clashes with rival Syrian rebels, a watchdog said on Tuesday.
The jihadists had apparently been executed after the fighting in the Jabal Zawiya district of the northwestern province of Idlib, the Syrian Observatory for Human Rights said.
The fighters, from ISIL and a group called Jund al-Aqsa, were killed by non-jihadist rebels over the past few days, the Observatory said.
The deaths came amid fighting on several fronts pitting several coalitions of rebel fighters against jihadists from ISIL.
There was renewed fighting on Tuesday in the city of Raqa, the only provincial capital outside government control and previously an ISIL stronghold, the Observatory said.
The fighting centred on the provincial governor’s office, taken over by ISIL for a headquarters, and “heavy weaponry was being used.”
Both Islamists and moderate rebels have joined the fight against ISIL, which has been accused of kidnapping, torturing and killing rival rebels and civilians.
The rebels, many of them civilians who took up arms against the regime, initially welcomed the arrival of battle-hardened jihadists.
But tensions have mounted, with activists accusing ISIL of imposing a reign of terror, and rebels saying the group has focused on accumulating territory and fighting other rebels rather than battling the regime.
Elsewhere in the country, the Observatory said the death toll from a government air campaign launched in Aleppo province in mid-December now topped 600, among them 172 children.
The relentless campaign has included the use of explosive-packed barrels dropped from aircraft on residential areas.