Dozens of people have been killed in an air strike on a village held by Islamic State in eastern Syria, activists say.

It was not clear who was behind the attack in Khansaa in Hassakeh province, which left between 30 and 80 dead.

The Local Co-ordination Committees and the Syrian Observatory for Human Rights said Syrian military helicopters had dropped barrel bombs on a market.

But some residents alleged that warplanes from the US-led coalition battling IS had fired missiles.

Syrian government officials have so far not commented on the incident.

Activists and witnesses concurred that the target of the strike in Khansaa, south of the Kurdish-held city of Qamishli, was a busy livestock market.

Resident Khair al-Obeidi told the Reuters news agency that the Syrian air force had bombed a part of the market where cattle were traded.

"There are at least 65 bodies - mostly charred bodies - that were counted by local medics in Tal Hamis," he said, referring to a nearby town.

The LCC, an opposition activist network, said at least 77 people had been killed in the attack and dozens wounded.