A preliminary assessment showed that the alleged use of chemical weapons in Syria "was a credible allegation", said the Hague-based Organisation for the Prohibition of Chemical Weapons (OPCW) on Thursday.
Chairperson of the OPCW executive council, Ambassador Odette Melono of Cameroon, in consultation with the Director-General of the OPCW Ambassador Ahmet Uzumcu, convened a meeting of the council to discuss these allegations, Xinhua news agency reported.
"The Director-General shared with the council the immediate steps taken by technical secretariat experts to analyse the available information and their preliminary assessment that this was a credible allegation," said the UN watchdog on chemical weapons.
The OPCW fact-finding mission has collected samples, which have been sent to OPCW designated laboratories for analysis. OPCW experts are currently analysing all information gathered from various sources.
The Director-General called on state parties that are in a position to do so to share with the Secretariat any relevant information without delay and allow the experts to complete its work within the next two to three weeks.
On April 4, a reported toxic gas attack hit the rebel-held town of Khan Sheikhoun in Syria's Idlib, killing over 80 people and wounding scores of others.
Two days later, the United States launched 59 cruise missiles against the Shairat military base in central Syria, from where, as the US believes, Syrian airplanes carrying chemical weapons took off.
The Syrian government denied the accusation. It said that its air strikes hit an arms depot containing toxic gas and blamed the rebels for storing such chemical materials.