China has imposed anti-subsidy duties for five years on imports of U.S. chicken products after concluding producers received improper support, the Commerce Ministry said Wednesday amid a string of trade spats with Washington.

Importers must pay tariff rates ranging from 4 percent to 30.3 percent on U.S. broiler or chicken products, starting Aug. 30, the ministry announced. The ministry said producers benefited from government subsidies that lowered feed prices and hurt Chinese competitors.

The tariffs apply to chicken parts and whole birds but not to live chickens or cooked products such as chicken sausage.

The announcement was the final ruling in a case announced earlier this year.

Among major producers, Tyson Foods Inc. is required to pay 12.5 percent duty, Pilgrim's Pride Corp. 5.1 percent and Perdue Farms Inc. 7.4 percent, the ministry said.

China imported 305,600 tons of U.S. chicken products in first half of last year, the ministry said on its website. Imports were 584,000 tons for all of 2008.

Products from the U.S. accounted for 89.2 percent of China's chicken product imports in the first half of 2009, the ministry said.

Beijing and Washington also are embroiled in disputes over access to each other's markets for steel pipes, movies and books and other goods.

The trade disputes have proliferated as governments try to boost exports amid weak demand. The two governments have accused each other of protectionism that they say could slow a global recovery.