AKIPRESS.COM - China has released documents it claims offers "ironclad proof" that the Japanese military forced Asian women to work in frontline brothels before and during the second world war, The Guardian reported.

Almost 90 documents from the archives of the military police corps – part of Japan's Kwantung army, the occupying force that propped up a puppet regime in Manchuria in the early 1930s – include letters from Japanese soldiers, newspaper articles and military files discovered in the 1950s and kept at the Jilin provincial archives in north-east China. Documents from the regime's national bank were also included.

"Going through the bloodiest parts of these archives, many of us experts have succumbed to chronic depression," said the archive's director Yin Huai, according to the official China News Service.

Zhao Sujian, 81, an archive employee since 1948, said that the documents were discovered by a People's Liberation Army unit in November 1953. The soldiers were digging near the remains of the Japanese base to lay pipes and fix electric cables when they stumbled on the buried cache.

"At the time, these documents filled an entire truck," he told the news service. "Because they were buried for so long, most of them were stuck together, even rotted into one mass."

The archive in Changchun, the provincial capital, began systematically analysing the documents in 1982, after it received them from a local law enforcement office. Most remain untranslated. Research has been slow, state media said, owing to the poor quality of the documents and a dearth of Japanese-speaking researchers.