The Organization for the Prohibition of Chemical Weapons said Wednesday its investigators have determined chlorine was likely used in a February attack in northern Syria.
The group based its report on interviews with health workers and witnesses as well as tests of samples from the site of the attack in the Saraqeb area of Idlib province.
At the time, medical groups and first responders reported civilians had signs consistent with chlorine gas, including breathing problems and the smell of chlorine on their clothes.
U.S. Ambassador to the U.N. Nikki Haley accused Syrian President Bashar al-Assad's forces of carrying out a chemical weapons attack on the rebel-held area.
The OPCW's mandate extends only to determining whether chemical weapons were used and not to identifying who was responsible.
Syria's government has repeatedly denied using chemical weapons throughout the conflict that began in March 2011.