The world's chemical-weapons watchdog says a substance used in an April 7 attack on a rebel-held town in Syria appeared to be a chlorine-based gas but that it has so far found no evidence of a nerve agent.
The Organization for the Prohibition of Chemical Weapons (OPCW) on July 6 said that "various chlorinated organic chemicals” had been found after its teams took more than 100 samples from seven sites in Douma outside of Damascus.
"Work by the team to establish the significance of these results is ongoing," the OPCW added.
Chlorine, a toxic industrial gas, is not specifically listed as a chemical weapon but its use as a weapon is a violation of international law.
Emergency crews said about 40 people were killed and hundreds hospitalized in the April 7 attack on then rebel-held Douma from exposure to chlorine and sarin gas. Western powers blamed the incident on Syrian forces.
Within days, U.S., British, and French forces launched retaliatory missile strikes against alleged chemical-weapons sites in Syria.
Following the attack, a UN investigation said evidence pointed to the use of chlorine but that some people had exhibited symptoms more consistent with exposure to a nerve agent.
Damascus and its ally Russia denied that Syrian government forces had conducted a chemical attack and accused rebels and the White Helmets rescue group of simulating the attack.
Previous UN-OPCW investigations have found that Syrian government forces used both sarin and chlorine, while Syrian rebel forces once used sulphur mustard gas.