South Korea's trade watchdog decided on Thursday to raise anti-dumping tariffs on polyethylene terephthalate (PET) film products imported from two Chinese companies, citing the need to protect domestic companies' market share.

The Korea Trade Commission (KTC) said it made a final decision to increase anti-dumping duties on PET film products imported from China's Kanghui New Material Technology Co. to 7.31 percent from the current 2.2 percent, reports Yonhap news agency.

Duties on those imported from Tianjin Wanhua Co. will be hiked to 36.98 percent from the current 3.84 percent, it added.

The re-examination request was made by four Korean companies, including Kolon Industries Inc. and Hyosung Chemical Corp., in February.

PET films are widely used in various industries, such as packaging, electronics and energy.

It marked the first case in which the KTC conducted a re-examination of anti-dumping duties at the request of domestic producers and determined the current tariff rates should be modified.

"We reached such a decision as the volume of dumping exports (of the Chinese companies) to Korea will likely increase and raise their market share here," a KTC official said.

Meanwhile, trade watchdog last month held separate public hearings on suspected damage to local companies in two ongoing anti-dumping cases involving Chinese and Japanese firms.

The hearings hosted by the Korea Trade Commission (KTC) follow preliminary decisions to impose anti-dumping duties of up to 33.57 percent on hot-rolled alloy and steel plates imported from China and Japan, and a 43.35 percent tariff on Chinese optical fibers.

Both of the duties are effective until January. An investigation was launched after a local steelmaker, Hyundai Steel Co., filed a complaint in December against six Japanese firms and five Chinese producers of hot-rolled alloy and steel plates for alleged dumping.

The other investigation, launched in March, came after LS Cable & System Ltd., South Korea's largest cable manufacturer, filed a complaint in early January, alleging that three Chinese companies sold single-mode optical fiber products at below fair market value.