All 193 OPCW Member States, Including Russia, are parties to the Chemical Weapons Convention.
The world's chemical weapons watchdog said on Tuesday that it was "concerned" over reports of the use of chemical weapons in the besieged Ukrainian port of Mariupol.
Reports first emerged Monday from Ukraine's Azov battalion that a Russian drone had dropped a "poisonous substance" on troops and civilians in Mariupol.
"The Technical Secretariat of the OPCW is monitoring closely the situation in Ukraine. The Secretariat is concerned by the recent unconfirmed report of chemical weapons use in Mariupol, which has been carried in the media over the past 24 hours," the Organisation for the Prohibition of Chemical Weapons (OPCW) said in a statement.
"This follows reports in the media over the past few weeks of shelling targeted at chemical plants located in Ukraine, together with accusations levelled by both sides around possible misuse of toxic chemicals.
"All 193 OPCW Member States, including the Russian Federation and Ukraine, are parties to the Chemical Weapons Convention, an international treaty of major importance in the field of disarmament that has been in force since 1997.
"In doing so, they have solemnly and voluntarily committed never to develop, produce, acquire, stockpile, transfer or use chemical weapons."
US President Joe Biden warned last month of a "real threat" Russia may use chemical weapons in Ukraine, repeating earlier allegations from the White House.
The last time chemical weapons were unleashed during a conflict was in Syria where a civil war erupted in 2011 as rebels sought to oust President Bashar al-Assad.
Syria only publicly admitted in 2012 that it possessed chemical weapons after pressure from Russia.
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