Japan said Friday it will impose antidumping duties of up to 13.5 percent on South Korean companies and 10.3 percent on Taiwanese firms for exporting polyester staple fiber at what it alleges are unfair prices.

Twenty-six South Korean and 13 Taiwan companies will be subject to the duties, officials of the Ministry of Economy, Trade and Industry said following a joint investigation into the case with the Finance Ministry that began in April last year.

The decision will be formalized Tuesday at a Cabinet meeting.

The antidumping tariffs will be the first imposed by Japan since August 1995, when it imposed similar levies on cotton yarn from Pakistan.

Polyester staple fiber is used to stuff quilts and for carpets.

According to the government findings, South Korea's Samheung Co. was found exporting the fiber at a dumping margin of 6 percent. The remaining 25 South Korean producers will be charged an identical 13.5 percent in additional tariffs due to lack of evidence that can be used to identify individual dumping margins, the officials said.

Four firms -- Sam Young Synthetics Co., Sung Lim Co., Dae Yang Industrial Co. and Huvis Corp. -- were found not to have dumped the fiber.

The 13 Taiwan firms, meanwhile, will all be levied 10.3 percent.

The combined value of the dumped exports came to around 591 million yen in fiscal 2000.

Under World Trade Organization rules, countries are permitted to impose antidumping duties for up to five years if they find export prices are set lower than prices in the exporters' home market and cause damage to the local industry.

According to the survey, the firms dumped a combined 6,465 tons in the three years to March 2001, up 38.8 percent, and their share of the domestic market in the period was 7.8 percent, up 1.9 percentage points.

During the same period, Japanese manufacturers suffered a 12.7 percent decline in prices, a 1.3-percentage point slip in market share to 89.1 percent, and an 8.9 percent sales decline, making their production unprofitable.

In light of rising imports of cheaper products, five large Japanese textile makers, including Toray Industries Inc. and Teijin Ltd., asked the government to impose the duties.

The manufacturers said the price of their polyester staple fiber fell 13 percent from fiscal 1997 through 1999 and their sales slipped 8 percent.

In April, the government had extended the probe for three months, citing additional documents submitted by the South Koreans.