SOUTH BEND, Ind. — Three environmental groups are trying to stop BP from continuing its expansion of an oil refinery along Lake Michigan, contending in an appeal to the state Monday that an air permit granted to the company was improperly granted.

The Natural Resources Defense Council filed the appeal with the Indiana Office of Environmental Adjudication on behalf of the Save the Dunes Council, the Sierra Club’s Hoosier chapter, the Hoosier Environmental Council and two Lake County residents. The groups argue that the state Department of Environmental Management made numerous factual and legal errors in granting the permit.

The appeal contends that the expansion would lead to large amounts of air pollutants being emitted, including nitrogen oxides, sulfur dioxide, carbon monoxide and carbon dioxide, and volatile organic compounds. The groups contend that the pollutants will adversely affect the health and welfare of people living in the area.

BP has said the expanded refinery would be the nation’s top processor of heavy high-sulfur Canadian crude oil, boosting its annual production of gasoline, diesel fuel and jet fuel by 15 percent to about 4.7 billion gallons annually. Some 1,700 people work at the 119-year-old refinery.