THE HAGUE, Netherlands (AP) — The global chemical weapons watchdog opened an emergency meeting on Thursday to discuss the situation in Syria over concerns about the country's stockpile of toxic chemicals in the wake of the overthrow of President Bashar Assad.

The Organization for the Prohibition of Chemical Weapons on Monday told Syria that it is under obligations to comply with rules to safeguard and destroy dangerous substances, such as chlorine gas, after rebels entered the capital, Damascus, over the weekend.

“Chemical weapons have been used in Syria on multiple occasions and victims deserve that perpetrators that we identified be brought to justice and held accountable for what they did and that investigations continue,” Fernando Arias González, the OPCW secretary general, said in his opening remarks.

“Our reports over the past few years have reached very clear conclusions and we hope that the new circumstances in Syria will allow this chapter to be closed soon,” he added, referring to the lack of stockpile declarations and the use of the weapons themselves.

Assad's government has denied using chemical weapons but the OPCW found evidence indicating their repeated use by Syria in the grinding civil war. Earlier this year, the organization found the Islamic State group had used mustard gas against the town of Marea.

In a rare move, the OPCW's executive council called the meeting, hoping that under a new government, some of its 80 inspectors may be allowed to pursue investigations into Syria's chemical weapons program.

Members of the ousted Syrian government plan to gradually transfer power to a new transitional Cabinet headed by Mohammed al-Bashir, who reportedly headed the rebel alliance's "salvation government" in its southwest Syrian stronghold.

Arias González also expressed concern about ongoing Israeli airstrikes in Syria.

“We do not know yet whether these strikes have affected chemical weapons related sites. Such airstrikes could create a risk of contamination. Another real risk would be the destruction of valuable evidence for investigations by different independent international bodies related to past use of chemical weapons,” the Spanish diplomat said.

The last time the OPCW called an extraordinary meeting was in 2018, in response to the chemical attack on Douma, a town close to Damascus, when some 40 people were killed by poison gas. Last year the watchdog found that the Syrian Armed Forces dropped canisters of chlorine gas during a major military operation.

Syria joined the OPCW in 2013 to ward off the threat of airstrikes in response to a chemical attack on the outskirts of Damascus.

The OPCW's 193 member states are required to disclose their chemical weapons programs and dismantle them. The organization, created in 1997 by the Chemical Weapons Convention, seeks to eliminate all chemical weapons. In 2013, it was awarded the Nobel Peace Prize for its work.