The United Nations chemical watchdog OPCW said Monday it had warned Syrian authorities to make sure suspected stockpiles of chemical weapons were safe after the overthrow of Syrian leader Bashar al-Assad.
The OPCW said it had contacted Syria "with a view to emphasising the paramount importance of ensuring the safety and security of all chemical weapons related materials and facilities" in the country.
Syria agreed to join the OPCW in 2013 shortly after an alleged chemical gas attack killed more than 1,400 people near Damascus.
It handed over its declared stockpile for destruction but the OPCW has always been concerned that the declaration made by Damascus was incomplete and that more weapons remained.
"To date... the Syrian declaration of its chemical weapons programme still cannot be considered as accurate and complete," said the OPCW.
"Serious concerns have remained about the completeness of Syria's initial declaration and the fate of significant amounts of chemical weapons unaccounted for," added the group.
The OPCW said it was prepared to work with the authorities in Syria and other international partners to address these concerns.
Taking control of Syria, the Islamist Hayat Tahrir al-Sham (HTS) group pledged its "readiness to cooperate with the international community in everything related to monitoring weapons and sensitive areas."
The group also said it would safeguard the country's remaining chemical weapons stockpiles and ensure it would not be used against citizens.
"We clearly state that we have no intention or desire to use chemical weapons or any weapons of mass destruction under any circumstances," the HTS-led "department of political affairs" said.
"We will not allow the use of any weapon, whatever it may be, against civilians or become a tool for revenge or destruction," HTS said, according to SITE, a private US organisation monitoring extremism on the internet.
"We consider the use of such weapons a crime against humanity," the HTS said, adding it would secure all military sites and "will not allow these sites or weapons to fall into irresponsible hands under any circumstances."
Earlier Monday, Israeli Foreign Minister Gideon Saar said his country had struck "chemical weapons" in neighbouring Syria "in order that they will not fall in the hands of extremists."