The Syrian Observatory for Human Rights also reported that 11 civilians were killed in a government air raid on the rebel-held town of Irbin northeast of Damascus.

And an airstrike in northwestern Syria killed at least nine militants from the Nusra Front on Sunday in an area near the Turkish border, the same group said, adding that four of the dead were foreign fighters.

The clashes that erupted on Saturday as ISIS launched an offensive aimed at seizing Tal Tamr in Hassakeh province from Kurdish forces have killed 40 fighters on both sides, it said.

“Fierce battles broke out during the past 24 hours around Tal Tamr… that killed 40 fighters,” said Observatory director Rami Abdel Rahman.

He said the fighting erupted when ISIS advanced close to the town, but the Kurds called in reinforcements and were able to repel the jihadis.

ISIS has been trying to capture Tal Tamr because of its strategic location.

Taking it would allow ISIS to dominate a key road between the eastern part of Hassakeh and the town of the same name that are held by the Kurds, and also gain access to the Iraqi border and the jihadi bastion in Mosul beyond.

Sunday’s raid on Irbin near Damascus during which missiles were fired at the town also wounded 50 people, some of them critically, the Observatory said.

It also reported several civilians wounded in government-held areas of Damascus by rebel rocket fire, without giving a precise toll.

Elsewhere, clashes were still under way around the Aleppo province villages of Handarat and Bashkoy between government forces and fighters from the Al-Qaeda affiliate, the Nusra Front.

The Observatory said that a child and a local Nusra commander were killed in the fighting.

A military source told AFP that loyalist forces had launched an overnight offensive on rebel positions in Handarat after failing to recapture it last month.