By Takuya Karube

TOKYO, Aug. 2 Kyodo -- A former soldier of a biological warfare unit of the Imperial Japanese Army believes he has a duty to tell the truth about Japanese war crimes committed in China during World War II as part of his effort to apologize for his deeds and because much of what happened is still unknown.

Yoshio Shinozuka, 78, has spoken about his war experiences across the country over the decades, vowing not to remain silent about the activities of the notorious Unit 731.

The secret unit is believed by some historians to have conducted germ warfare against the local population and used some 3,000 Chinese and other prisoners of war as test subjects for biological experiments.

"I am conscious of having conducted something unforgivable as a human being," Shinozuka said at a recent talk in Tokyo.

Shinozuka joined Unit 731 in the spring of 1939 at the age of 15 without knowing about what kind of work it was involved in.

Upon becoming part of the unit, which was operating near the northern Chinese city of Harbin, he was ordered to keep everything secret.

"Don't look. Don't listen. Don't tell. That was the golden rule of the unit,'' Shinozuka said.

The initial training he had to undergo was to learn how to produce germs and cultivate fleas, and the first germs produced in mass quantities were used in the Nomohan Incident between Japanese and Soviet near the Chinese and Mongolian border in 1939, he said.

The Soviet forces defeated the Japanese army in the military conflict that took place from May to September, and the defeat was a major setback for those advocates in the army who promoted confrontation with the Soviet Union rather than with the United States.

Unit 731 was active from around 1936 in the former Manchukuo, a puppet state that the Japanese controlled from 1932 to 1945 in the northeastern Chinese region traditionally called Manchuria.

Shinozuka said he himself was involved in vivisections, and that people who were killed for experiments were called ''logs'' or ''maruta'' in Japanese.

''We said in the unit we chop one log, two logs..human beings were synonymous to logs..what I was involved in were very serious war crimes,'' he said.

Shinozuka came back to Japan in August 1956 after spending six years in prison camps for war criminals in China.

Notwithstanding his unpardonable crimes, Shinozuka received humane treatment while in the camps, he said.

After his return, Shinozuka worked as a public servant for the Chiba prefectural government. He occasionally had a chance to speak about his war experiences.

But social climate was still difficult at the time. There were not many people who wanted to listen to his stories.

Recalling those days, Shinozuka said, ''There were many accounts of war victims, but accounts from victimizers were unwelcome.''

''If I spoke of the brutality of the Imperial Japanese Army, people would have told me that I had stayed too long in the Chinese camps and was brainwashed,'' he said.

Shinozuka clearly remembers the faces of victims of the vivisections, saying he cannot keep quiet about how their lives were stolen in such a barbaric manner.

''I admit my guilt and have thought over what I did.'' He began seriously telling his stories in the early 1980s shortly before his retirement.

Shinozuka has visited China a number of times, cooperating also with 180 Chinese victims of the biological warfare experiments who filed a joint lawsuit seeking damages and apologies from the Japanese government.

A ruling in the suit will be handed down on Aug. 27 at the Tokyo District Court, and he has lately been unsettled about whether justice will be served.

Even though he was invited by human rights groups to speak in the United States and Canada in June 1998, he was barred from entering the U.S. at the airport in Chicago because he was considered to be a war criminal.

Shinozuka has come a long way, but he is aware that the road to peace is never smooth.

''Biological weapons are devilishly cruel, and their cruelties are not only in the past,'' said Shinozuka. ''We must avoid the same mistake.''

''By confessing and revealing what we have done in China, we can pursue the war crimes and responsibilities of the Japanese government,'' Shinozuka added.