Cambodia Files OPCW Complaint Over Alleged Chemical Substance Use by Thai Forces

PHNOM PENH, Sept 14, 2026 (KPT) — Cambodia has lodged a formal complaint with the Organisation for the Prohibition of Chemical Weapons (OPCW) over alleged use of chemical substances by Thai forces during two rounds of conflict, officials said. Cambodian Mine Action Centre (CMAC) director general Heng Ratana told reporters on September 11 that the complaint was submitted to the OPCW secretariat in The Hague, which oversees compliance with the Chemical Weapons Convention (CWC). Ratana alleged Thai forces deployed chemical substances via aircraft, drones and artillery, including 155mm and 100mm shells. He said CMAC had identified 43 types of commonly used weapons during operations since July 2025, particularly after renewed fighting in December. Remnants were found near Preah Vihear Temple, rice fields and residential villages. According to Cambodia’s Ministry of Health, 399 civilians were affected by toxic substances, while Cambodian soldiers and police officers also suffered injuries. Both Cambodia and Thailand are parties to the CWC, which bans the use of chemical weapons. Ratana stressed the distinction between chemical weapons and chemical substances, noting their legal definitions differ under the convention. The filing marks Cambodia’s effort to elevate its allegations to an international body tasked with enforcing the global ban. Officials say the move underscores concerns over civilian protection and compliance with humanitarian law, as Phnom Penh seeks international scrutiny of the clashes and their aftermath.