Syrian civil war
Syrian civil war Reuters

The Syrian regime has used chemical weapons against rebel-held areas neighboring Damascus, according to rebel sources.

Opposition activists claim that "Syrian regime forces" launched "a series of chemical attacks" on the Damascus suburbs of Adra and Houma, early Monday morning.

Posting videos they said were from the scene of the attacks, activists claimed that more than 400 people had shown "signs of exposure to chemical toxic gasses, ranging from shortness of breath, seizure, convulsion, profuse sweating ...copious nasal secretions and frothy sputum."

One resident of Adra told the Arabic-language Al Arabiya channel that the attacks occurred during early morning prayers.

"During the time of prayer we smelled something resembling sulfur and were certain we were being bombarded with chemical weapons," he said, claiming that worshippers promptly donned gas masks.

Last week, the UN announced that the Syrian regime would allow inspectors to visit three sites of alleged chemical weapons use by both the army and rebel forces.

On Monday, Human Rights Watch slammed the Assad regime for its use of ballistic missiles against densely-populated areas. Nine ballistic missile attacks over the course of just six months lone are believed to have killed at least 215 people 

The alleged chemical attacks came on the same day as rebels seized four key villages in the regime stronghold of Latakia, according to the Syrian Observatory for Human rights.