BEIRUT: Syrian rebels have killed a Kurdish woman militia leader in the northern city of Aleppo, highlighting growing tensions between anti-regime fighters and the Kurds, a monitoring group said Friday.

"Shaha Ali Abdu, also known as Nujeen Dirik, was killed early on Friday. She headed a Kurdish popular defence unit that is part of the Democratic Union Party (PYD)," Syria's branch of the Kurdistan Workers' Party (PKK), said the Syrian Observatory for Human Rights.

"She was killed a week after she was captured by rebels," the Britain-based watchdog added.

The PYD opposes the regime of President Bashar al-Assad but has taken a neutral position in ongoing fighting in embattled Aleppo, the country's commercial hub.

Clashes between the rebels and Kurdish militia in Aleppo reportedly left 30 dead last week, sparking fears of a new front in the already fractured country.

According to the Observatory, 42-year-old Dirik was captured when she went to hand over to the rebels the bodies of opposition fighters killed in the fighting.

Dirik headed a militia unit charged with protecting the Ashrafiyeh and Sheikh Maqsud districts of Aleppo, said Rujhad Khalil, an Aleppo journalist who specialises in Kurdish affairs.

Kurdish fighters were "on a mission to deliver the bodies of opposition fighters, as well as rebels taken hostage, after clashes between Kurdish militia and anti-regime insurgents" when she was captured, Khalil said.