UPDATE 2-US piles more duties on Chinese, Indonesian paper

* New duties are in addition to ones announced in March

* U.S. imported $213.3 million of paper from China in 2009

* Asia Pulp & Paper says duties 'un-American' (Adds background)

By Doug Palmer

WASHINGTON, April 29 (Reuters) - The United States on Thursday slapped additional preliminary duties on hundreds of millions of dollars of glossy magazine-quality paper from China as Sino-U.S. trade disputes continued to pile up.

The Commerce Department said it hit Chinese companies with new duties ranging from 30.82 percent to 135.8 percent and Indonesian firms with a 10.62 percent duty.

The decision is another victory for U.S. companies NewPage Corp [NEWPG.UL], Appleton Coated LLC and S.D. Warren Co, and for union workers, who filed a request last year for relief.

"We think it's an excellent result. It shows that these producers have really engaged in unfair trade and that the United States government is really willing to impose significant duties to offset that unfair trade," said Gilbert Kaplan, an attorney at King & Spalding for the U.S. industry.

Asia Pulp & Paper [SINAMS.UL] said in a statement it had been hit with a 30.82 percent anti-dumping duty on its exports from China and 10.62 percent from Indonesia.

Terry Hunley, acting president of APP Americas, expressed confidence the U.S. International Trade Commission would eventually strike down the duties, as happened in a similar case it faced several years ago.

"There are no merits to the petitioners' accusations and restricting competition in the paper industry is un-American and will hurt U.S. printers and all consumers of coated paper products," Hunley said.

The United States imported $213.3 million of coated paper from China in 2009 and $46.9 million from Indonesia.

The anti-dumping duties announce on Thursday were in response to evidence of the paper being sold in the United States at below fair market value.

They are on top of countervailing duties of 3.92 percent to 12.83 percent for China and 17.48 percent for Indonesia announced in March to offset government subsidies.

China has accused the United States of misusing its trade laws to impose duties on an array of Chinese goods, including passenger tires and many steel products.

Washington says the duties are justified to protect vulnerable U.S. companies against unfair Chinese trade practices, like subsidies or below-market prices.

In a sign that trade frictions go both ways, this week Beijing imposed countervailing duties on U.S. poultry products on top of anti-dumping duties it had already set.

The coated paper case has additional significance because it includes a claim that China is subsidizing its export by maintaining an "undervalued" currency.

The Commerce Department has not officially decided to investigate the issue. But under pressure from members of Congress, has said it might. That would likely anger Beijing who sees its exchange rate as an internal matter.

The department's final calculation of countervailing duties is due in mid-July and U.S industry hopes it will have decided by then to offset China's exchange rate policy.

The final decision in the anti-dumping phase of the investigation is in September.

The U.S. International Trade Commission has the final word in both cases whether duties are imposed. It can reject duties if it decides U.S. producers are not threatened or harmed by the low-priced imports. (Reporting by Doug Palmer; editing by Mohammad Zargham)