A U.S. steelmaker and the United Steelworkers of America labor union have filed an antidumping petition alleging that Japanese companies are exporting stainless steel angles to the United States at unfair prices, industry sources said Friday.

The complaint, filed by Indiana-based Slater Steel Inc. and the labor union, is the 12th lodged by the U.S. steel industry against Japanese-made steel products with the Commerce Department and the International Trade Commission, the sources said.

Stainless steel angles are used in construction.

Rulings on the previous 11 petitions have resulted in punitive duties being imposed on seven types of Japanese steel product -- hot-rolled steel sheets, stainless steel sheets, stainless steel wire rods, steel plate products, structural steel beams, seamless steel pipes and tin products.

The U.S. government has dismissed petitions against stainless steel round wire, cold-rolled steel and concrete reinforcing steel bars and, most recently, seamless stainless pipes.