United States Steel Corp. said late Tuesday that it will temporarily idle its Great Lakes Works plant in Ecorse and two other facilities in a move to reduce production amid falling demand for its steel products.

The action will affect roughly 3,500 workers at the three plants, the Pittsburgh-based company said. Great Lakes employs about 2,005 people. The plant produces sheet products primarily for the automotive industry.

Over the next several weeks, U.S. Steel is also idling Keetac, an iron ore mining and pelletizing facility in Keewatin, Minn., and Granite City Works near St. Louis.

U.S. Steel, which has more than 49,000 employees, said it plans to temporarily concentrate production at Mon Valley Works near Pittsburgh; Gary Works in Gary, Ind.; Fairfield Works near Birmingham, Ala.; and Lake Erie Works in Nanticoke, Ontario.

"The largest percentage of employees (affected) are union workers, but this idling cuts across all categories: hourly, management and professional," said D. John Armstrong, manager of public affairs.

Armstrong could not project how long the idling would last, only that it would be determined by market conditions.

U.S. Steel products are used in a number of fields, including the automotive industry, appliance manufacturing, construction industry sheet products, containers and oil and gas piping applications.

The idling follows the company's announcement in mid-November that it laid off 185 people at Great Lakes Works as part of 675 cuts in the U.S. and Canada.

"We believe that our difficult decision to temporarily consolidate our production is a necessary response to current market conditions," said U.S. Steel Chairman and Chief Executive John Surma about its latest announcement.

Benefits for a majority of the laid-off workers are defined by labor agreements with the United Steelworkers union, Armstrong said, but include health insurance for a certain length of time based on length of service.

U.S. Steel gained 26 cents to $27.75 in after-hours trading, after jumping $1.85, or 7.2 percent, to $27.49 during the regular session. The stock has traded between $20.71 and $196 during the past 52 weeks.