A Syrian rebel group accused government forces Saturday of dropping a barrel bomb containing poisonous chemicals on civilians in eastern Ghouta, and a medical relief organization said 41 people had been killed in chemical attacks on the area.

Syrian state media denied government forces had launched any chemical attack as soon as the reports began circulating and said rebels in the eastern Ghouta town of Douma were in a state of collapse and spreading false news.

The U.S. State Department said Saturday reports of mass casualties from an alleged chemical weapons attack in Douma were "horrifying" and would, if confirmed, "demand an immediate response by the international community."