Japan sought out and looted mineral resources in northeast China as early as after the Sino-Japanese War of 1894-1895, according to over 2,000 files released by the Liaoning provincial geological archives.

The files include records of mine exploration and related photos of the Japanese, said Li Dongfeng, deputy head of the archives.

"The Japanese researchers involved in the prospecting were mostly experts. Their search area covered more than 2,000 mines in Liaoning," Li said. "They found 61 types of mines in the area, accounting for about half of the province's present known resources."

Files showed exploration activities by Japanese invaders started after the Sino-Japanese War broke out in 1894.

"It shows Japan's looting of Chinese resources was a deliberate and long-planned move," Li said.

The archives sorted out the files and translated them into Chinese to be published on its official website.

The Japanese also expanded the scale of their steel plants in Liaoning's Anshan City, where they found iron mines, to supply the steel demand during the invasion, said Zhong Xiangfei, an official with the Angang Group, one of China's major steelmakers.

Japanese troops began invading northeast China on September 1931, and then attempted to turn Anshan into an iron and steel center for the puppet Manchurian regime, Zhong said.

It was recorded in files that Japanese invaders had looted more than 10 million tonnes of iron and steel resources from Anshan City during the period from 1916 to 1945, according to Zhong.