Tokyo - Japan plans to complain to the World Trade Organization this week over South Korea's plan to regulate the manufacturing and sale of lithium-ion batteries, a government official said Monday.

South Korea was expected to start applying new rules requiring foreign firms obtain approval from Seoul to produce and sell products with lithium-ion batteries in South Korea as of July 1.

Japan expressed concerns that South Korea's new system would interfere with Japan's battery exports.

"We fear the new regulation, if introduced, could amount to a trade barrier for foreign companies," Minister of Economy, Trade and Industry Toshihiro Nikai said.

Japanese companies account for about 60 per cent of the world's market, Jiji Press said. (dpa)