At least 32 people were killed in Syrian regime air raids on two rebel-held towns near Damascus on Sunday, a monitoring group said.

Syrian Observatory for Human Rights head Rami Abdel Rahman said 17 people were killed in Douma, northeast of the capital, and 15 others in Kfar Batna, to the east of Damascus.

A woman and a child were killed in each of the towns targeted, he said.

The rebel bastion of Douma has been besieged by regime forces for more than a year, and it has been the target of regular bombardment over past weeks.

Activists on the ground confirmed Sunday's air raids, saying that markets had been the targets.

Both towns are in the Eastern Ghouta region in the east of Damascus province.

Syria's more than three-year war is estimated to have killed more than 170,000 people and displaced around half of the population.