The OPCW experts analyzed samples of mustard gas, employed in the August 2015 attack, saying that there’s ground to believe that “this substance may have been produced by ISIS (ISIL, IS, Daesh) itself,” Uzumcu told AFP.

The officials stressed that the terrorist-made substance was “poor quality, but still harmful,” adding that it was an “extremely worrying” development.

“Especially, given the fact that there are several foreign fighters in those countries, who may go back to their countries of origin one day.

This requires a high-degree of vigilance within our countries,” Uzumcu said.

The OPCW chief stressed that there has been “more than 20”allegations of chemical weapons use coming from both the Syrian government and the so-called “moderate” rebels since August 1.

The sides blame each other for the “use of chlorine and unidentified agents in Aleppo and in northern parts of Syria,” including Idlib, he said.

The OPCW received Syrian government’s freshest reports of chemicals weapons used by the militants on Thursday, according to Uzumcu.

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