U.S. steelmakers and the United Steelworkers union took aim at one of their biggest customers yesterday, calling efforts of U.S. automakers to blame their woes on steel import restrictions laughable.

DaimlerChrysler, Ford, General Motors, Honda, Nissan and Toyota are lobbying the U.S. International Trade Commission to remove tariffs that have been in place since 1993 on imports of corrosion-resistant steel from Japan, Canada and four other countries. The sheet steel is used largely in automobiles and appliances.

Automakers allege the duties harm the competitiveness of U.S. manufacturers by limiting their access to lower-cost foreign steel. The tariffs were imposed after federal officials determined the low-priced foreign steel violated U.S. trade law.

"There is no longer an economic basis for keeping these duties. The steel industry benefits from unnecessary protection while the duties hurt a much wider sector of the U.S. economy," said Toyota group vice president Josephine Cooper.

Blaming a product that accounts for about $400 of the cost of a $30,000 car "is a total red herring," said Robert Lighthizer, an attorney who represents U.S. Steel and AK Steel in trade cases. The problems of General Motors and Ford have more to do with health care, litigation costs and currency manipulation, said Mr. Lighthizer. He called GM, AK Steel's largest customer, "a basket case."

Ford and GM "have a lot of other problems and they're striking out at whoever they can," he told reporters during a conference call.

U.S. Steel senior vice president Terrence Straub said the foreign automakers with U.S. plants are doing quite well "and they're doing that by buying American steel."

The ITC will hold a hearing on the tariffs Oct. 17 and will vote in December whether to lift them or keep them in place.