Lawsuits seeking to halt mining at coal mines in three states could have sweeping consequences on the coal industry. The lawsuits have been filed by the environmentalist group WildEarth Guardians which is seeking to change the approval process for mine on federally owned lands.

The Associated Press reported that the suits in Colorado, New Mexico and Montana assert that the coal mining companies won approval for the mines through lax oversight by federal regulators.

The group says the U.S. Department of Interior approved mining plans without enough public involvement and gave little heed to the pollution caused by digging, shipping and burning coal.

The lawsuits asked the courts to stop mining until the plans are redone.

The cases involve the San Juan coal mine in New Mexico, the Colowyo and Trapper mines in Colorado and the Spring Creek Mine in Montana.

The National Mining Association has intervened in the Montana case on behalf of Spring Creek operator Cloud Peak Energy, of Wyoming and stated that if the lawsuits are successful mines across the United States could be threatened.

The four mines at the heart of the case employed about 1,200 workers and produced 27 million tons of coal last year, according to federal records.

Attorneys for the federal government denied the environmentalists' claims and have asked the courts to dismiss the cases.

New Mexico-based WildEarth Guardians has a lengthy record of litigation against the coal industry.