But such joint digs and collections have been going on for nine years, and so far not a single weapon has been destroyed, Xinhua news agency said.

A Chinese chemical weapons expert align poison gas bombs dug from a pit in Ning'an, northeastern China's Heilongjiang province, July 5, 2006. A joint Chinese-Japanese team was preparing Wednesday to excavate abandoned Japanese poison gas bombs from World War II that were buried near a school after a factory received them as scrap metal. [AP]

"We are rather dissatisfied with Japan's slow pace of disposal," Chinese official Liu Yiren was quoted as saying.

A total of 689 shells and bombs were unearthed in Ning'an in the northeastern province of Heilongjiang, of which 210 were confirmed to be chemical weapons, Xinhua said.

Chinese harbour deep bitterness over Japan's invasion and occupation of large parts of the country between 1931 and 1945, and accuse modern-day Japanese leaders of failing to acknowledge atrocities committed by the Imperial Army.

Present-day Heilongjiang in 1932 became part of a Japanese puppet state in an area then known as Manchuria.

"The identified weapons have been confirmed to be filled with mustard gas, lewisite, phosgene and other toxins," Xinhua said.

The weapons had been sealed and placed in temporary storage, awaiting final destruction, according to the office in charge of abandoned weapons at China's Foreign Ministry

China says Japan abandoned at least 2 million tons of chemical weapons at about 40 sites in 15 provinces at the end of the war, most of them in the three northeast provinces of Heilongjiang, Jilin and Liaoning.

Japan puts the figure in the hundreds of thousands.

In the past nine years, China and Japan have worked together to retrieve and pack the dumped weapons.

So far, 37,499 chemical weapons and 200 tons of contaminated items had been collected, but none had been destroyed, Xinhua said.

In 2003, a man was killed and 43 injured when five canisters of Japanese mustard gas were disturbed at a construction site in Heilongjiang province.