Chemical weapons attacks have killed dozens on the outskirts of Damascus, Syrian opposition activists claim.
Rockets with toxic agents were launched at the suburbs of the Ghouta region in the early hours of Wednesday morning, they say.
Footage uploaded to YouTube by activists shows many people being treated in makeshift hospitals.
A team of UN inspectors arrived in Syria on Sunday to probe earlier allegations of chemical weapons use.
It is not clear whether the inspectors will look into the latest allegations. They are due to investigate three locations, including the northern town of Khan al-Assal, where some 26 people were killed in March.
Both the rebels and government forces have accused each other of using chemical weapons during the conflict.
It is not possible to independently verify the claims.
Syria is widely believed to possess large undeclared stockpiles of mustard gas and sarin nerve agent.
Source: BBC