"The panel is confident that the Syrian Arab Republic is responsible for the release of sarin at Khan Sheikhun on 4 April 2017," stated the report seen by AFP yesterday.
More than 87 people died in the nerve gas attack on the town in Syria's northwestern Idlib province.
Horrific images from the immediate aftermath of the attack drew global outrage and prompted the United States to fire cruise missiles at a Syrian air base from which the West says the assault was launched.
Syria ally Russia maintains that the sarin attack was most likely caused by a bomb set off directly on the ground, not by a Syrian air strike as alleged by the West.