The founder of Green Cross Corp., an Osaka-based pharmaceutical firm, played a major role shortly after World War II in preventing senior members of Unit 731 from being prosecuted as war criminals, it was learned Friday.

Ryoichi Naito, a physician and key member of the unit, drafted a plan in which unit leaders would hand over to the U.S. military most of the information related to the unit's efforts to develop biological and chemical weapons.

However, Naito said information concerning their planned germ warfare and vivisection should never be disclosed, according to recent discoveries in the documents.