Updated

Activists say infighting between rebel forces in Syria has killed at least 50 in clashes in the country's northeast.

The Syrian Observatory for Human Rights said Thursday that the fighting took place in Hassakeh province.

It says clashes between Kurdish fighters and members of the Al Qaeda-linked Nusra Front and the Islamic State in Iraq and the Levant in the past two days left 13 Kurdish gunmen and 35 militants dead.

The two sides have been fighting in northern Syria for months in clashes that left scores of people dead on both sides.