The world's chemical weapons watchdog said on Friday that all declared stockpiles have been "irreversibly destroyed" after the US revealed it had finally got rid of the last of its toxic weapons.

US President Joe Biden announced that Blue Grass Army Depot, a US military base in Kentucky, has eliminated its decades-old stockpile, completing a global effort launched in 1997 to rid the world of chemical weapons .

The destruction of all declared chemical weapons stockpiles is an important milestone in this direction, Fernando Arias, head of the Organization for the Prohibition of Chemical Weapons (OPCW), said in a statement. The Hague-based body said the move by the US, which was the last possessing country of chemical weapons, meant that all declared chemical weapons stockpiles had been irreversibly destroyed. But the OPCW, a Nobel Peace Prize laureate, warned that the recent use of chemical weapons means the world still needs to be vigilant.

The watchdog has in recent years accused Syria of chemical attacks during its civil war and has investigated the use of powerful Soviet-era agents in Britain against Alexei Navalny, a former Russian spy and Kremlin rival in Russia.

Arias warned that the recent use of toxic chemicals as weapons and threats show that preventing its re-emergence will remain a priority for the organization.