China will raise anti-dumping duties on optical fiber imports from two Republic of Korea (ROK) companies after re-examining their dumping margins, the Ministry of Commerce said Friday.

Starting from March 5, the duty rates for certain optical fiber products imported from LS Cable & System Ltd. and Taihan Fiberoptics Co., Ltd. will be increased to 9.1 percent to 7.9 percent, respectively, the MOC said in an online statement.

The MOC launched a review of previous anti-dumping tariffs for the two companies on March 5, 2012 at the request of Chinese industry players. The ministry said the new rates were based on calculations of the two companies' dumping margins in the past year.

China started to impose five-year anti-dumping tariffs on certain optical fiber products imported from Japan and the ROK in 2005. After a review of the ruling, it extended the measures for another five years in January 2011.

The target product, the dispersion unshifted single-mode optical fiber, or G652 single-mode optical fiber, is the most commonly used optical fiber in the manufacturing of telecommunications products.