Japan has again been forced to confront its wartime conduct after a former doctor in the country's imperial navy admitted he had conducted experiments on Filipino prisoners during the second world war. Akira Makino, 84, said in an interview with the Kyodo news agency that he had performed surgery and amputations on dozens of prisoners of war before they were executed in the Philippines. Mr Makino is one of several former Japanese soldiers who decided to reveal the truth about their country's use of human guinea pigs before they die. Unit 731, the imperial Japanese army's notorious germ warfare unit, killed thousands of Chinese civilians and Allied PoWs at its sprawling complex in Harbin, northern China. The victims ... were injected with typhus, cholera and other diseases. They died during the experiments or were executed to prevent them from talking about their experiences. As the end of the war approached, the unit destroyed evidence of their activities. The extent of their activities only came to light following testimony from repentant former doctors, soldiers and nurses. US authorities secretly granted unit officials immunity from prosecution in return for access to years of research into biological weapons. Several former Unit 731 officials went on to enjoy prominent careers in medicine, academia and business. Mr Makino ... said he remained haunted by memories of the experiments. We should not repeat that misery again," he said. "I want to tell the truth about the war."