THE HAGUE // Chemical weapons experts have determined that mustard gas was used in a Syrian town where ISIL militants were battling another group, according to a report by an international watchdog.A confidential report dated October 29 by the Organisation for the Prohibition of Chemical Weapons (OPCW) concluded “with the utmost confidence that at least two people were exposed to sulphur mustard” in the town of Marea, north of Aleppo, on August 21.