U.S. Steel Corp. has begun a program of laying off white collar workers that could affect 5 to 10 per cent, or 2,500 to 4,500, of its 45,000 salaried workers.

And National Steel Corp. is laying off 600 workers in two Detroit area plants.

U.S. steel president David Rosderick said in Pittsburgh Wednesday that the layoffs will continue through March 31.

The cutback will affect between 300 and 600 of the 6,000 employees at the nation giant steel makers' Pittburgh headquarters.

"We are tightening up our belts," Roderick said. "When business is bad, we always tighten up our belts.

Roderick said the company plans no reductions in total steel-producing capacity during the current retrenchment.

He also said the outlook was "dismal" for the firm's plant in Youngstown, Ohio, where the company employs about 6,000 workers. Youngstown Sheet and Tube Co. recently announced the layoff of 5,000 workers at its plant in the Mahoning Valley near Youngstown.

The U.S. Steel president said earnings for the year will be below those recorded in 1976, and that demand for the firm's products were on a "very low plateau."

National Steel's reduction, made in its Great Lakes Steel division, brings to 60,000 the number of steel workers laid off across the country in recent weeks.

The affected workers are at Great Lakes' Ecorse and River Rouge plants. Many work at the furnaces that turn ore into iron and iron into steel. One of Great Lakes' four blast furnaces will be shut down.

"The heavy influx of foreign steel into Detroit ports is a major factor" in the layoffs, said Robert D. McBride, Great Lakes president.