THE HAGUE, April 9 (Xinhua) -- The Organization for the Prohibition of Chemical Weapons (OPCW) is investigating the alleged use of chemical weapons during the attack in Douma, Syria on April 7, it stated Monday.

According to an official statement, the OPCW has closely monitored the incident and has made a preliminary analysis of the reports of the alleged use of chemical weapons. The fact-finding mission now is in the process of gathering further information from all available sources to establish whether chemical weapons were used.

Activists, local rescuers and rebels in Syria claim that Syrian forces used chlorine gas in the attack on Saturday against Douma, in the rebel-held area near Damascus. The Syrian government has denied the allegations and called it fake news.

Since its establishment in 2014, the OPCW fact-finding mission has been investigating allegations of the use of chemical weapons in Syria by interviewing witnesses and obtaining samples and physical evidence for analysis. Its mandate is to determine whether chemical weapons have been used, not who is responsible for the alleged attacks.

In June last year, the OPCW concluded after investigation that chemical weapons were used on April 4, 2017 in the Khan Shaykhun area, Idlib Province in Syria.

The Chemical Weapons Convention prohibits the use of chemical weapons. The United Nations Security Council will hold an emergency meeting on Monday to discuss the alleged chemical weapons attack.