China Tuesday extended by six months the anti-dumping investigation on mostly-used optical fiber imported from the United States, Japan and the Republic of Korea.

The target product, the dispersion unshifted single-mode optical fiber, accounts for about 70 percent of the total used optical fiber in the world, according to the ministry.

The Chinese Ministry of Commerce said that the case, initiated on July 1, 2003, was more complex than other anti-dumping cases.

Based on Chinese anti-dumping regulations, the ministry said it decided to extend the investigation to Jan. 1, 2005.

In 2002, China imported 110 million US dollars worth of optical fiber from the United States, Japan and the ROK, according to the ministry.