A chlorine gas attack has been carried out on a besieged rebel-held enclave on the outskirts of the Syrian capital Damascus, reports say.
People in the Eastern Ghouta region, which is under daily bombardment, reported a smell of gas after a missile strike, the BBC has learned.
Health workers said six people were treated for minor breathing problems.
Some 400,000 locals have been under siege from Russian-backed government forces since 2013.
There have been a number of reports of chlorine gas attacks since Syria’s civil war broke out, but the government has always denied using chemical agents.
On 10 January the UN’s high commissioner for human rights said an upsurge in air strikes and ground attacks had killed at least 85 civilians in Eastern Ghouta since 31 December.
“In Eastern Ghouta, where a crippling siege has caused a humanitarian catastrophe, residential areas are being hit day and night by strikes from the ground and from the air, forcing civilians to hide in basements,” Zeid Ra’ad al-Hussein said in a statement.
The Eastern Ghouta region is strategically important, as rebels based there are able to fire rockets into residential neighbourhoods of Damascus. This has also caused civilian deaths, according to state media.