Beirut (AFP) - At least 23 civilians, including eight children, were killed in regime air raids on a market in a jihadist-held city of eastern Syria on Monday, a monitoring group said.

"Regime military aircraft fired at least two missiles at a souk (market) in Mayadeen, killing at least 23 civilians including eight children and five women," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

He said 50 others were wounded in the raids on Mayadeen, located in Syria's oil-rich Deir Ezzor province and held by jihadists from the Islamic State group.

The group had given an earlier toll of 15 dead.

On Sunday, the Observatory reported that IS had shut down playgrounds in Mayadeen "under the pretext that there was mixing between men and women bringing their children to play".

The ultra-radical organisation has imposed its extreme interpretation of Islam in areas under its control across swathes of Syria and Iraq.

Regime air strikes also killed four civilians in Kfarbatna, a town in the rebel bastion of Eastern Ghouta near Damascus, the Observatory said.

And two people died inside the capital itself when opposition fighters fired shells onto a district, Syria's official news agency SANA said.