The Syrian Observatory for Human Rights said Tuesday's bombardment of Eastern Ghouta had killed at least 47 people. The activist-run Ghouta Media Center said at least two, Douma and Harasta, was struck by ground-to-ground missiles.
The Syrian Civil Defense search-and-rescue group, which works in opposition areas, says it is "another bloody day for civilians" in Eastern Ghouta.
The region has been under intense attack since the end of December as the government of President Bashar Assad struggles to bring it under control.
Syria's multi-sided war has drawn in armies and insurgents from around the world, aggravating a conflict which began as an uprising against Assad's rule.
In a broadcast with the word "urgent" superimposed, it said at least 30 people had been killed and that airstrikes are still underway in the Ghouta.
In recent days, the situation in parts of Syria has decayed, particularly in Idlib province, where Russia's Aerospace Forces have been attacking jihadists from the Nusra Front terrorist group (outlawed in Russia), which hit an aircraft during its Saturday overflight of the Idlib de-escalation zone. Though he appears to have survived the insurgency, his forces continue to bomb and besiege opposition pockets across Syria, including in eastern Ghouta and Idlib. It said one of its workers was killed by an airstrike while attempting a rescue in the area.
The US proposed a draft statement condemning the use of chemicals as a weapon, but Syrian government ally Russian Federation added amendments that made no mention of the attack, according to a draft seen by AFP. "We contact them in real time or in advance".
United Nations officials in Syria called for fighting to stop to enable aid deliveries and the evacuation of sick and wounded, listing seven areas of concern including northern Syria's Kurdish-led Afrin region, being targeted by a Turkish offensive.
Turkey's military said a Turkish soldier was killed in an attack in Idlib, where its troops are establishing an observation post.
The Turkish General Staff in a statement said one of the soldiers was killed in a mortar attack by People's Protection Units (YPG) militants in the YPG-held Afrin's Kuri Hill region.