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 within the Eastern Ghouta region, which will be 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 coming from Russian-backed government forces since 2013.
There have been several reports of chlorine gas attacks since Syria’s civil war broke out, yet 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 in addition to 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 in addition to night by strikes coming from the ground in addition to coming from the air, forcing civilians to hide in basements,” Zeid Ra’ad al-Hussein said in a statement.
The Eastern Ghouta region will be strategically important, as rebels based there are able to fire rockets into residential neighbourhoods of Damascus. This particular has also caused civilian deaths, according to state media.
Yusuf Ibrahim, a teacher who currently lives underground within the rebel-held town of Harasta, just outside Eastern Ghouta, described the situation there.
“Today will be not so difficult as the idea was yesterday because there are no warplanes or any raids till currently, just heavy artillery bombardments … like surface-to-surface rockets, which are targeting the buildings in addition to the population in Harasta,” he told the BBC.
“The inhabitants of the city are all underground, living within the basement or the cellars because of such heavy bombardment.
“There will be no means of life such as markets or Great services.”
Last week, aid workers said at least 10 hospitals in rebel-held areas of Syria had suffered direct air or artillery attacks within a 10-day period.
An adviser to a coalition of medical charities told the BBC the attacks had been the most intense for a year.
Food shortages have led to many cases of severe malnutrition, in addition to a UN report in November said some residents in Eastern Ghouta had been reduced to eating animal fodder in addition to even rubbish.
Several are reported to have died of starvation.
Eastern Ghouta will be one of several “de-escalation” zones in Syria announced by Russia, Iran in addition to Turkey in 2017.
Despite that will, the area has remained under bombardment. Troops in addition to allied militia have also shut many of the routes used to smuggle in food in addition to medicine, leaving residents dependent on irregular aid deliveries.