UNITED NATIONS, Oct. 22 (UPI) -- The Syrian government launched a chemical weapons attack in 2015, a confidential report to the United Nations Security Council said.
The leaked report by the Organization for the Prohibition of Chemical Weapons blames Syria's President Bashar al-Assad for dropping barrel bombs containing chlorine gas from military helicopters, according to Voice of America.
The report was the group's fourth in a 13-month-long investigation sent to the U.N. Security Council and contained "sufficient evidence" confirming the government's role in a March 16, 2015 strike on Qmenas in the north-west province of Idlib.
An earlier report in the ongoing OPCW investigation blamed the Syrian government for two other gas attacks in 2015, the BBC reported.
Syria joined the 1997 Chemical Weapons Convention in 2013 and agreed to destroy its chemical weapons, including chlorine weapons which are prohibited.
The report stated the weapons could have originated from two bases belonging to the 63rd helicopter brigade in Syria, although the inquiry "could not confirm the names of the individuals who had command and control of the helicopter squadrons at the time."
The report said "officials must be held accountable" as US ambassador to the UN, Samantha Power, described the use of chemical weapons as "barbaric" and called for "all states to support strong and swift action."
"The UK will continue to work with the international community to pursue an end to the regime's indiscriminate bombing campaign, full and sustained humanitarian access, an immediate and lasting ceasefire, and a return to the negotiating table," he said.