A set of clothes believed to have been worn by sex slaves working at a wartime military brothel in Japan have been confirmed to be government-made, yet more evidence of direct state involvement in the sexual slavery system, the country's archives said Wednesday.

The National Archives of Korea said it has confirmed the Japanese army's clothing agency made the two pieces of clothes recovered in 2007 by a South Korean scholar from what used to be a navy airport in the Japanese prefecture of Nara.

The scholar, Kim Moon-gil, a Japanese language professor at Busan University of Foreign Studies, donated the clothes to the National Memorial Museum of Forced Mobilization under Japanese Occupation in 2016, and the museum asked the National Archives in February this year to conduct preservation treatment on them before putting them on public display.

In the course of the treatment, the National Archives traced where the clothes were made, and confirmed they were produced and distributed by Japan's army. That represents proof that Japan's government operated military brothels, Kim said.

The National Archives said it has completed preservation treatment of the clothes for five months and returned them to the museum. The museum in the southern city of Busan plans to put the clothes on display on Liberation Day on Aug. 15.

Historians estimate that up to 200,000 women, mainly from Korea, which was a Japanese colony from 1910 to 1945, were forced to work in front-line brothels for Japanese soldiers during World War II. Japan has long attempted to water down the atrocity. (Yonhap)