Four elderly veterans spoke from Tokyo about atrocities committed during Japan's occupation of China. A global Internet audience was able to monitor the event which was beamed to the Simon Wiesenthal Center's Museum of Tolerance in Los Angeles.

Shiro Azuma, who took part in what became known as the Rape of Nanking, confessed he had killed 37 women, children and elderly people.

"We were able to kill them because we despised them," he said. "We didn't respect their rights. The Japanese army in general did not respect human rights at all."

As many as 300,000 people were killed as the then-capital Nanking was looted and burned after its capture in 1937.

"I am so sorry, I would like a judge to punish me. That is the only way I can repent," said a comrade, Hakudo Nagatomi.

Germ warfare experiments

Another soldier, Yoshio Shinozuka, told how he helped to develop germ warfare while stationed with a medical unit in occupied Manchuria.

He had raised infected fleas on rats and cultivated typhoid, anthrax, plague and cholera to be used against the Soviet army.

An historian taking part in the event, Sheldon Harris, said more than 10,000 people had been killed in lab experiments and perhaps 250,000 in biological attacks in China.

Questions were e-mailed to the veterans or posed by the audience in Los Angeles.

The organiser of the event, Rabbi Abraham Cooper, praised the moral courage of the men in speaking out and the presence of members of the Japanese media after some of their politicians had insisted atrocities had never taken place.