Ten people have been killed in Syria by government air strikes and shelling on a town in the suburbs of Damascus, the Syrian Civil Defence rescue organisation said.

The group, also known as the White Helmets, said government forces targeted Kafr Batna early on Wednesday with air strikes, artillery fire, and barrel bombs — crude, explosives-filled oil drums dropped from helicopters at high altitudes.

The latest deaths followed intense shelling that killed nearly 130 people in two days earlier this week, marking the deadliest bombardment of the region in three years.

The locally-run Ghouta Media Centre reported strikes on Kafr Batna and other towns in the rebel-held eastern Ghouta region outside Damascus.

Activists said there has been no let-up to the waves of shelling on eastern Ghouta since government and Russian forces stepped up their assault late on Sunday.

The Syrian Observatory for Human Rights says at least 250 civilians have been killed.