United Nations war crimes investigators for Syria on Friday underscored the importance of preserving evidence related to an alleged chemical attack in the rebel-held town of Douma.
"We stress the imperative need to preserve evidence, and call upon all relevant authorities to ensure no party tampers with suspected sites, objects, witnesses, or victims before independent monitors and investigators are able to access the area," the UN's Independent International Commission of Inquiry on the Syrian Arab Republic, (COI), said in a statement.
The COI, established by the UN Human Rights Council, has been regularly compiling evidence of serious international crimes committed in the Syrian conflict since 2011.
The panel was the first UN entity to definitively blame Syrian President Bashar al-Assad's regime for a chemical attack which killed dozens of people in the town of Khan Sheikhun in April 2017.
The COI recalled that it has documented 34 incidents of chemical weapons use "by various parties to the conflict".
It said that it welcomed the fact that the Organisation for the Prevention of Chemical Weapons (OPCW) was deploying to Syria to investigate Saturday's attack in Douma and that Damascus has promised "full and unfettered access and freedom of movement" to OPCW staff.
COI investigators have never been granted access to Syria.
Western officials believe chlorine was used in the attack on Douma, the main city in the longtime rebel bastion of Eastern Ghouta, where the British government now estimates 75 people were killed.
