HARBIN -- Chinese experts recently uncovered more than 40 items in Southwest China's Yunnan province that offer fresh evidence of Japanese germ warfare activities during World War II.

The findings came from field research in May that focused on 15 War of Resistance against Japanese Aggression sites and some areas strongly impacted by germ warfare in Yunnan province, said Yang Yanjun, a researcher with the Harbin Academy of Social Sciences who studies Unit 731, the Japanese troops' biological warfare unit.

The items included protective clothing against biological chemicals, rat cages and injection syringes, Yang said.

"These items show that the Japanese army had taken protective measures to keep themselves immune from plague, anthrax and cholera," said Yang.

Yang said further information is required to determine the unit affiliated to Unit 731 and how deep it was involved in germ warfare in Yunnan.

The results of the research confirmed that Japanese military forces launched biological attacks in Yunnan when they invaded the region in May 1942.

Japanese troops also dropped cholera and pestilence germs into wells, ponds and ditches along a highway linking Yunnan and neighboring Myanmar as well as bacteriological bombs throughout towns and cities in the province, Yang said.

It is estimated that some 200,000 local Chinese residents were killed in the Japanese germ attacks in the western part of Yunnan, said Chen Zuliang, a germ warfare expert from Yunnan.

Unit 731 was a secret biological and chemical weapons research and development unit of the Japanese army. It was responsible for some of the most notorious war crimes during Japan's invasion of China, including human experimentation.