Cambodia has filed a complaint with the Organisation for the Prohibition of Chemical Weapons over allegations that the Thai military used chemical weapons and chemical substances during last year's border conflict, Cambodian media reported.
The complaint was filed on September 11 following findings by the Cambodian Mine Action Centre, which said 395 Cambodian civilians and security personnel were affected by the alleged substances, according to the Phnom Penh Post.
Heng Ratana, director-general of the centre, said the substances were allegedly delivered by aircraft and drones as well as through 155mm and 120mm artillery shells.
Evidence was found in civilian areas, including a market, villages and farmland, he said.
“Chemical weapons and chemical substances were used. From a technical perspective, these are two different terms,” the Phnom Penh Post quoted Ratana as saying.
Thailand rejects the allegations
The centre also cited an analysis of 61 chemical samples from August 2025, classifying one finding as a chemical weapon under the Chemical Weapons Convention and 22 as toxic or hazardous chemicals not prohibited by the treaty.
The complete laboratory report and sampling methodology were not presented during the briefing.
Thailand has previously rejected Cambodian allegations that its forces used chemical weapons.
Thailand's foreign ministry in July 2025 called the allegations “groundless” and part of a campaign of disinformation.
The Royal Thai Army later also rejected claims involving white phosphorus munitions, saying they are not classified as chemical weapons under the Chemical Weapons Convention.
