Organisation for the Prohibition of Chemical Weapons (OPCW) chief Ahmet Uzumcu revealed Friday (November 18th) that experts with his organisation believe the "Islamic State of Iraq and the Levant" (ISIL) may have manufactured mustard gas used in Syria and Iraq, AFP reported.

Samples of mustard gas taken from attacks in Syria and Iraq have now been analysed by the OPCW's dedicated laboratories and "the findings do suggest that this substance may have been produced by ISIL itself", Uzumcu said.

It was "poor quality, but still harmful ... and it was weaponised so it is extremely worrying" the OPCW chief said, speaking exclusively to AFP after the UN Security Council extended the mandate for another year of a special joint UN and OPCW panel to allow them to investigate more reported chemical attacks in Syria.

The global watchdog tasked with destroying chemical weapons also is probing more than 20 reports of the alleged use of toxic arms in Syria since August, Uzumcu said, including some allegations made as recently as Thursday.

Since August 1st, he said, there had been a number of allegations, by the Syrian regime and the opposition, of the "use of chlorine and unidentified agents in Aleppo and in northern parts of Syria" such as Idlib.

The OPCW is already "collecting information and analysing" it, he added, to see if the allegations "are credible or not in order to deepen our investigation".