BEIRUT, August 21 (The Associated Press) – Two Syrian pro-opposition groups are claiming that government forces carried out a "poisonous gas" attack near the capital Damascus, leaving dozens of people dead.

The two groups quote activists as saying that regime forces fired "rockets with poisonous gas heads" in the attack on Wednesday.

The Britain-based Syrian Observatory for Human Rights says the shelling was intense and hit the eastern suburbs of Zamalka, Arbeen and Ein Tarma.

It says "tens of people" were killed. The Local Coordination Committees said hundreds of people were killed or injured in the shelling. Such different figures are common in the immediate aftermaths of attacks in Syria.

There was no government comment on the claims and the reports could not be independently confirmed.