WASHINGTON — The Bush administration filed a complaint with the World Trade Organization yesterday accusing China of providing companies with improper subsidies that hurt U.S. firms.

The action came as the administration faced increased pressure from the Democratic-controlled Congress to do something about the nation's soaring trade deficits and lost manufacturing jobs, which critics blame in part on unfair trade practices by foreign nations.

The complaint alleges that China uses WTO-illegal tax breaks to encourage Chinese companies to export more to the United States while imposing tax and tariff penalties to limit purchases of U.S. products in China.

"We are seeking to level the playing field to allow U.S. manufacturers to compete fairly with Chinese firms," U.S. Trade Representative Susan Schwab said in announcing the case.

"The United States believes that China uses its basic tax laws and other tools to encourage exports and to discriminate against imports of a variety of American manufactured goods," Schwab said.

The decision to go to the WTO with a trade complaint will trigger a 60-day consultation during which trade negotiators will try to resolve the dispute. If that fails, a WTO hearing panel will be convened and if the U.S. wins, it will be allowed to impose sanctions on Chinese products.

Schwab's announcement came two days after Treasury Secretary Henry Paulson faced questioning before a congressional panel about deficits with China, which are at all-time highs.

While an official with China's delegation to the WTO in Geneva said the Chinese would have no immediate comment, members of Congress and U.S. business groups praised the action.

"Forcing China to eliminate its illegal subsidies will keep world markets open to U.S. goods, keeping jobs at home," said Senate Finance Committee Chairman Max Baucus, D-Mont.

"This case represents a step in the right direction, but it must be part of a much more aggressive program to take actions against violation of WTO obligations," said Rep. Sander Levin, D-Mich., and the head of a House Ways and Means trade panel. John Engler, the former Michigan governor who is now head of the National Association of Manufacturers, said he was disappointed other major trading partners, including Japan and the European Union, refused requests to join in filing the case.

"We hope that other countries will reconsider ... recognizing it is not fair to have the United States do all the heavy lifting," Engler said.