DULUTH, Minn. — A federal appeals court has put a hold on regulations aimed at reducing haze over national parks and wilderness areas from taconite plants in Minnesota and Michigan.

The stay was sought by Cliffs Natural Resources, which operates three taconite plants in Minnesota and one in Michigan, and ArcelorMittal, which runs another in Minnesota.

The Duluth News Tribune reports (http://bit.ly/19gDPcA ) the order, dated Friday, holds up final regulations issued in January by the U.S. Environmental Protection Agency. The rules would apply to all taconite plants in Minnesota and upper Michigan and require some to install expensive new equipment to reduce nitrogen oxide emissions.

U.S. Rep. Rick Nolan, D-Minn., says the order gives the plants more time to develop technology to solve the problem without forcing them into costly improvements too soon.