HAIKOU - Historical records of the South China Sea were opened to public in the southernmost province of Hainan on Monday.

The archives have about 30,000 items on the South China Sea accumulated from archives, libraries and academic institutions from the Chinese mainland, Taiwan and other countries.

The archives focus on the Republic of China (1912 - 1949), digging for historical and legal evidence for China's territorial claims in the South China Sea, said Wu Shicun, head of the National Institute for South China Sea Studies (NISCSS), which administers the archives.

The data base contains government documents, wire files, conference summaries, photos and maps, proving China's administration of the islands in the area before and after the World War II, said Wu.

Although the situation in the South China Sea is stable in general, negative and unstable factors are increasing, he said.

The archives will continue to accumulate and sort relevant materials, he said.

NISCSS is a research institution dedicated to the study of the South China Sea. It was founded as the Hainan South China Sea Research Center in 1996 and elevated to the national level in 2004.