Fresh fighting between the jihadist Islamic State of Iraq and a coalition of rebels and an Al-Qaeda affiliate in eastern Syria has left at least 45 fighters dead, a monitoring group said Monday.
ISIL, which grew from a former affiliate of Al-Qaeda in Iraq, has faced a backlash in opposition Syria since early this year and is battling a coalition including Al-Qaeda's Al-Nusra Front and Islamist and moderate rebels.
The Syrian Observatory for Human Rights said the clashes in the town of Khosham in the eastern province of Deir Ezzor left 17 Al-Nusra and Islamist fighters dead, along with 28 ISIL members.
The fighting began on Sunday and raged through the night, the Observatory said.
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ISIL was initially welcomed by some in Syria's armed opposition, but its harsh interpretation of Islam and abuses against civilians and rival opposition fighters has sparked a backlash.
Al-Qaeda's chief has called on the group to return to Iraq, and even Al-Nusra has turned against it, battling it across several opposition-controlled provinces in Syria.
The fight against ISIL has killed some 6,000 people since it began in early January, according to the Observatory, a Britain-based NGO.
Elsewhere in the country, the Observatory said at least 25 people had died under torture at security facilities in Damascus province.
Detainees are often held for interrogation at security facilities before being transferred to jail.
The group said the families of those killed were informed of the deaths and told to retrieve the bodies of their loved ones on Sunday.