According to Uzumcu, the use of sarin in February 2017 raised concerns that Syria might have kept certain banned substances despite Assad’s government saying it surrendered its stockpile of chemical agents in 2013. Syria could have also redeveloped or reacquired them.
“Many Western countries are worried that the Syrian government continues to possess some of the precursors of sarin,” he said.
The OPCW chief’s comments came after a number of deadly suspected chemical attacks by Syrian government forces. Syria and ally Russia consistently deny that such incidents have taken place, or say that rebels fighting to unseat Assad are responsible.
After a recent attack northeast of Damascus that activists and aid groups said killed dozens, Russia and Syria were accused of holding up inspections and tampering with evidence.
Uzumcu said a key issue hindering the OPCW’s work was that its current mandate was to only determine whether such attacks have taken place, and not who carried them out.
In November, a Russian veto stripped the organization of a mechanism that had allowed it to probe and assign blame when banned chemicals were used.