Experts from China and Japan concluded on Monday a six-day joint excavation of abandoned wartime chemical weapons in Ning'an city, Northeast China's Heilongjiang Province.

Huang Shunxiang, digs out a bomb at an excavation site of World War Two chemical weapons abandoned by Japan, in Ning'an, China's Heilongjiang province, July 5, 2006. The 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. [Reuters]

A total of 689 shells and bombs were unearthed, of which 210 were confirmed to be Japanese chemical weapons abandoned after World War II.

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

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

Chinese official statistics show Japan abandoned at least 2 million tons of chemical weapons at about 40 sites in 15 provinces at the end of World War II, most of them in the three northeast provinces of Heilongjiang, Jilin and Liaoning.

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

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

"We are rather dissatisfied with Japan's slow pace of disposal, " said Liu Yiren, director of the Japanese abandoned chemical weapons disposal office under China's Foreign Ministry.

Liu stressed that the weapons, some still lethal or toxic after decades, remained a threat nationwide, noting that leakages involving injury or death have occurred.

One person died and 43 were injured in Qiqihar, Heilongjiang, in one such incident last August. More than 50 bombs, including chemical weapons, were found last month in a village near the same city.

More than 2,000 Chinese have fallen victim to Japan's abandoned chemical weapons, killed by leading toxic gas while working at construction sites or on other occasions, according to China's Foreign Ministry.

"The facts have proved again we have come to a situation where no more delays can be tolerated," Liu said.

China and Japan have agreed to build a disposal facility for the destruction of retrieved chemical weapons in Ha'erba Ridge of Dunhua City, Jilin Province, neighboring Heilongjiang, where 670,000 chemical weapons have been confirmed dumped by Japanese troops.

So far Japan has not disclosed any detailed information about where they abandoned or buried their weapons, making it difficult for China to trace and remove them.

The lack of information has also led to incidents.

China and Japan joined the United Nations Chemical Weapons Convention in 1997. Two years later, they signed a memorandum, in which Japan admitted that it had abandoned a large amount of chemical weapons in China at the end of World War II.

Under the memorandum, Japan is obliged to remove the weapons by April 2007 and provide all necessary funds, equipment and personnel for their retrieval and destruction.

However, the Japanese government has asked for an extension of the disposal deadline to April 2012.

"Judging from Japan's current pace of weapons disposal, we can't be too optimistic about complete destruction by 2012," Liu said.

At the request of the Chinese government, Japan sent more than 20 experts Wednesday to the Ning'an site.