Though an international treaty banned germ warfare at that time, the army headquarters ordered it to be carried out in China. At the end of the war, the army tried to destroy evidence by demolishing Unit 731 facilities in northeastern China, according to military sources.

Details of Unit 731's activities came to light as a result of the disclosure of wartime U.S. government records and testimony by former unit members.
China waived its claims for compensation when it established diplomatic relations with Japan in 1972, in exchange for the Japanese government's expression of "deep remorse and full realization of its responsibility" in the China-Japan Joint Communique. (Compiled from news reports)

Courtesy of Japan Today http://www.japantoday.com

Please also read a related article:
Japan: Ex-Unit 731 Member Spreads Truth as His Apology, by Takuya Karube
http://www.unobserver.com/index.php?pagina=layout5.php&id=303&blz=1