"Four member states have declared to have chemical weapons in their possession: the Russian Federation, the United States, India and a fourth state that does not want to be named," Director General Rogelio Pfirter told journalists.

"By April 29, all four possessor states will have destroyed the percentage of munition and chemical agents that they have committed themselves to reduce under the (1993 chemical weapons) convention."

Based in The Hague, the OPCW brings together 151 member states that have signed the 1993 convention, which aims to eliminate chemical weapons by 2007.

Russia had the largest chemical stockpile, with 40,000 tonnes, and has undertaken to destroy one percent of that by April 29.

The United States had 28,000 tonnes of chemical weapons and has successfully destroyed 20 percent of its stocks, fulfilling its undertaking to the OPCW.

According to the OPCW, both India and the fourth, anonymous state have fulfilled their objectives.

Pfirter added that Albania had undertaken to destroy a stash of recently discovered chemical weapons, apparently dating from the Cold War era.

He lamented the fact that various countries in the Middle East had not yet ratified the convention to eliminate chemical weapons.

Syria, recently accused by Washington of possessing chemical weapons, has not signed the convention, but is seeking to put a resolution to the UN Security Council calling for the Middle East to be chemical-weapon free.

Commenting on the Syrian move, Pfirter said that "all initiatives are welcomed", but added that the OPCW already existed for the same purpose.

SPACE.WIRE