The Harbin City Government will enforce a regulation from Tuesday to intensify the preservation of the site of former Japanese troop Unit 731 to expose the crimes of the Japanese invaders and call for peace across the world, according to an official statement.

Under the regulation approved by the provincial legislature of Heilongjiang in northeast China, the protection includes the headquarters of the largest biological warfare team in the world, a factory producing shells containing biological agents, a liaison office on Jilin Street, a dormitory, the then-Japanese Consulate, single and group structures and their facilities in the suburban testing ground Chengzigou as well as other mobile and immobile cultural relics displayed at the site.

Established in 1939 as a top-secret biological warfare research base of the Japanese Kwantung Army, the unit was the nerve center of Japan's biological warfare in Southeast Asia during the Second World War. More than 10,000 civilians and war prisoners from China, the former Soviet Union, the Democratic Republic of Korea and Mongolia died as the subjects of experiments conducted by Unit 731.

When the Soviet army took back Harbin in 1945, the Japanese blew up the base.

In October 2000, 900-plus pages of confidential documents belonging to Unit 731 about experiments conducted in northeast China were discovered by a Japanese scholar in a library's warehouse of a medical college in Japan.

The documents contain key research showing that the troop had spread pestis bacteria in northeast China's cities of Nong'an and Changchun in the 1940s.

The records detail the way the pestis bacteria was produced and spread, the conditions of the affected viscera and the relationship between plague and climate.