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At least 25 Syrian rebels were killed overnight in an attack by Islamic State group (IS) fighters on a rebel stronghold in Aleppo province, a monitoring group said on Tuesday.

Fighting lasted until dawn on Tuesday in Marea, one of the most significant rebel bastions in the divided province. The town sits on a road linking eastern Aleppo city and the border with Turkey.

At least eight IS fighters were killed, according to the Syrian Observatory for Human Rights, "including four suicide bombers who blew themselves up with explosive belts".

Mamun al-Khatib, director of Shahba, an Aleppo-based activist news network, said in a Facebook post that "an IS cell infiltrated the town of Marea and its fighters bombed and fired upon civilians".

Rebel fighters surrounded the jihadists, prompting them to blow themselves up, Khatib added.

On Sunday IS fighters seized full control of Umm Housh, one of four villages in the northern province of Aleppo that lie along a rebel supply line from Turkey, which is a major backer of Syria's opposition.

At least 37 rebel fighters and 10 IS fighters died in the battle for the town, the observatory said.

The al-Qaeda-linked Nusra Front has ceded positions on the frontline against the IS in northern Syria to other rebel groups in advance of Turkey' creation of a buffer zone in the area.

According to a report released on Tuesday by the Syrian Network for Human Rights, the coalition's bombing campaign against the IS has killed 228 civilians. This number includes 65 children and 37 women since it began on 23 September 23, 2014. Three opposition fighters have also been killed.

More than 240,000 people have been killed in Syria since the conflict began with anti-government demonstrations in March 2011.