Syria's foreign ministry said on Saturday that a report by the Organization for the Prohibition of Chemical Weapons (OPCW) that found the Syrian government was responsible for a chemical weapon attack on the opposition-held Syrian city of Douma in 2018 lacked any evidence, and denied the allegations. The global chemical weapons watchdog said on Friday a nearly two-year investigation had found that at least one Syrian military helicopter had dropped gas cylinders onto residential buildings in Douma, killing 43 people. The April 7, 2018, attack on the outskirts of Damascus was part of a major military offensive that returned the area to the control of forces under Syrian President Bashar al-Assad after a prolonged Russian-backed siege against the opposition stronghold. A previous investigation by the OPCW had already concluded in March 2019 that a chemical attack had taken place in Douma, but that inquiry had not been mandated to assign blame. The latest inquiry identified four alleged perpetrators in one air force unit, but their names were not made public. The findings are based on technical analysis of 70 biological and environmental samples, satellite imagery, 66 witness interviews and ballistic and munitions testing, the OPCW said. "At least one helicopter of the Syrian Tiger Forces' Elite Unit dropped two yellow cylinders containing toxic chlorine gas on two apartment buildings in a civilian-inhabited area in Douma, killing 43 named individuals and affecting dozens more," a summary of the report said. The Tiger Forces are elite Syrian troops generally used in offensive operations in the war. "The world now knows the facts," said OPCW Director-General Ambassador Fernando Arias. "It is up to the international community to take action, at the OPCW and beyond."