Work began Saturday at a plant in Teshikaga, Hokkaido, to dispose of poison gas shells left by the Imperial Japanese Army at the end of World War II, officials of the Prime Minister's Office said.

The move is in line with an international convention that calls for the prohibition and restriction of the use of chemical weapons.

A total of 26 poison gas shells that were recovered from Lake Kussharo in the town in October 1996, have since been concrete-sealed within polyvinyl chloride containers and stored underground in a local forest. Experts had confirmed them as chemical weapons.

Workers will remove gunpowder from the shells' heads after neutralizing the poison in a plant set up by the office, the officials said. They will dispose of the gunpowder by burning it, the officials added.

On Saturday, engineers from Kobe Steel Ltd. and Ground Self-Defense Force members transferred one of the shells to a disposal unit and prepared to neutralize its poison.

The whole operation, which also involves participation by experts from the United States and Britain, is expected to take about two months.

In a related project, 75 Japanese -- consisting of government officials, private sector experts and GSDF members -- began a joint operation with a 200-strong Chinese team earlier this month to remove an estimated 500 poison gas shells left by the Imperial Japanese Army in the Chinese province of Heilongjiang.