The US is trying to establish what chemicals were used during gas weapon attack on the Syrian city of Douma, the Guardian reported.

According to the source, the US technicians are trying to establish whether the gas contained more than chlorine.

“Blood and urine will help to establish that for up to a week,” the source said quoting one official who had examined samples taken from patients.

As reported earlier, Syrian opposition activists, rescue workers and medics say more at least 49 people dead and dozens more injured on Saturday in a suspected chemical attack on the Syrian city of Douma.