A report by the Organization for the Prohibition of Chemical Weapons (OPCW) has concluded "with a high degree of confidence" that chlorine gas was used in attacks on three Syrian villages last year.
Western news agencies obtained a copy of this third report by an OPCW fact-finding mission on January 6.
The report did not apportion blame but said 32 of 37 people interviewed "saw or heard the sound of a helicopter over the village at the time of the attack with barrel bombs containing toxic chemicals."
The investigators said 26 people heard the distinctive "whistling" sound of falling barrel bombs and that 29 people smelled "the distinctive odor of the gas cloud."
The UN Security Council discussed the report on January 6.
The U.S. ambassador to the UN, Samantha Power, said this latest report provided "more compelling eyewitness evidence of chlorine gas use by the Syrian regime."