Hasakeh, Syria: Syrian government aircraft bombed Kurdish positions in the divided northeastern city of Hasakeh on Thursday, the first such strikes against a Kurdish-held area of Syria.

The strikes hit three Kurdish-manned checkpoints and three Kurdish bases, the Syrian Observatory for Human Rights said.

They came after heavy clashes broke out on Wednesday between Kurdish fighters who control two-thirds of the city and pro-government militia who control the rest.

The clashes have left 11 people dead — four civilians, four Kurdish fighters and three government loyalists, a medical source said.

The two sides share a common enemy in the Daesh terror group which controls most of the Euphrates valley to the south but there have been tensions between them in Hasakeh that have sometimes led to armed clashes.

The Kurds, who control much of northeastern and northern Syria along the Turkish border where they have proclaimed an autonomous Kurdish region, recently demanded that the pro-government National Defence Forces disband in Hasakeh.

A government source in the city said that the air strikes were “a message to the Kurds that they should stop this sort of demand that constitutes an affront to national sovereignty”.

The Kurdish People’s Protection Units (YPG) are a key US ally in the fight against Daesh.

Washington regards them as the most effective fighting force on the ground in Syria and has provided weapons and special forces military advisers.

Meanwhile, the UN envoy to Syria, Staffan de Mistura, said on Thursday that aid convoys have not reached Syria’s besieged areas with desperately needed food and medicine for the past month.

In protest at the failure of warring parties to allow aid to reach civilians, de Mistura cut short the weekly meeting of the Geneva-based humanitarian task force, which is headed by the United States and Russia.

“Not one single convoy in one month has reached any of the besieged areas,” de Mistura told reporters, blaming relentless fighting.

Thursday’s task force meeting lasted just eight minutes before it was “suspended”, de Mistura said, explaining that the move was symbolic and that the group would meet again next week.

The envoy reissued the United Nations’ call for a weekly 48-hour humanitarian pause in Aleppo, where an estimated 1.5 million civilians are trapped as fierce fighting rages between Syria President Bashar Al Assad’s forces and rebels.

Aleppo, Syria’s second city and former economic hub, has emerged as a top concern for the UN and aid agencies since regime troops seized control of the last supply route into rebel-held areas in mid-July.

De Mistura said the 17 countries that make up the International Support Group for Syria (ISSG), which sit on the humanitarian task force, would hold another meeting later on Thursday on the issue of a humanitarian pause in Aleppo.

Since the beginning of the year, the UN and its Red Cross partners have delivered aid to nearly 1.3 million Syrians living in areas defined as besieged or hard-to-reach.

But the movement of convoys has primarily been hampered by access restrictions imposed by Al Assad’s government.

Deir Al Zor, which is partially controlled by Daesh, has continued to receive aid over the last month through World Food Programme air drops, de Mistura said.

Four besieged areas — Madaya, Zabadani, Foah and Kafraya — have not been reached by a convoy in 110 days, the UN envoy added.

More than 290,000 people have been killed and more than half the population has been displaced since Syria’s conflict erupted in March 2011 with antigovernment protests that escalated into a brutal multi-front war.