The global chemical weapons watchdog says it has found "reasonable grounds" that chlorine was used as a weapon in an attack on the Syrian town of Douma last year.

The Organization for the Prohibition of Chemical Weapons issued a final report Friday of its Fact Finding Mission's probe into the attack on April 7, 2018.

The United States, Britain and France blamed Syrian government forces for the attack and launched punitive airstrikes. Syria denied responsibility.

The Fact Finding Mission's mandate does not include laying blame for the attack.