Experts from China and Japan on Wednesday began to recover more than 600 chemical weapons left by retreating Japanese troops during World War II, state media said.
The team will catalogue, pack and seal up the weapons within the next 12 days before they are placed in storage to await destruction, Xinhua news agency said.
The new batch of weapons was excavated in Wangkui county of Suihua city from June 27 to July 2 when workers were laying the foundations of a shopping mall, Xinhua said.
Some of the weapons have fuses.
On July 10, China and Japan completed an excavation of 210 chemical weapons, including mustard gas bombs and bombs packed with lewisite, phosgene and other toxins in Ning'an city in Heilongjiang province.
From February 1995 to April 2006, Chinese and Japanese experts retrieved 37,499 such weapons.
Beijing has been pressing Japan to work faster to destroy its abandoned chemical weapons.
Japan estimates its forces abandoned more than 700,000 chemical weapons in China during the war, although Chinese experts say there could be as many as two million.
Over 2,000 Chinese citizens have been injured or killed by leftover Japanese chemical munitions since the end of the war, Xinhua said.
Such mishaps invariably lead to a resurgence of anti-Japanese sentiment in China, where lingering anger over Japan's wartime past routinely sours relations.
Under the UN Chemical Weapons Convention, Japan is responsible for cleaning up the bombs. It has repeatedly expressed its willingness to do so although technical and diplomatic problems have held up progress.
