Forcing women into sex slavery and setting up "comfort stations" were official actions of the invading Japanese army during World War Two in Asian countries, newly publicized wartime archives reveal.

A total of 89 wartime documents were made public on Friday as a response to Japan's right-wing politicians' denial of its wartime crimes in China. Twenty-five files relate to "comfort women".

The use of "comfort women" was the state action of Japan during the war, said Su Zhiliang, a professor on the history of "comfort women" at Shanghai Normal University.

The actions harmed China, Republic of Korea and Democratic People's Republic of Korea.

The archives showed that the first "comfort station" was in the Southeast Asian country of Indonesia on Java Island.

The invading Japanese army in northeast China, documented what happened during the war, revealing their criminality.

The files are from archives of the military police corps of Japan's Kwantung Army and the national bank of the puppet Manchurian regime, which are stored in Jilin Provincial Archives in northeast China.

The 25 files on "comfort women" include two investigation reports, two telephone records and 21 documents on troops forcing women to have sex and enslaving them.

They revealed conditions at "comfort stations", including ratios between Japanese soldiers and "comfort women" and details of gruesome rapes.

The invading Japanese army allocated women proportionally.

In Feb. 1 to 10 in 1938, there were six "comfort women" for 1,200 soldiers, a ratio of 1:200, in Xiaguan district of east China's Nanjing. After Feb. 20, there were eleven more "comfort women", representing a ratio of 1:71.

In five months since November 1944, the invading Japanese army paid 532,000 Japanese yen on setting up "comfort stations". The expenditure was approved by the Kwantung Army, said a telephone record of the national bank of the puppet Manchurian regime.