CHARLESTON, W.Va. (AP) -- The United Mine Workers of America is suing Arch Coal and Peabody Energy over pension and health-care benefits for bankrupt Patriot Coal Corp.'s active and retired miners and their families.

Peabody spun off Patriot in November 2007. Patriot later acquired mines that Arch spun off into Magnum Coal.

The union's lawsuit says Arch and Peabody set up spinoff companies to rid themselves of their benefits liabilities. But it says they are still responsible for these benefits under the federal Employee Retirement and Income Securities Act.

Arch and Peabody declined to comment to media outlets on the lawsuit.

Patriot filed for Chapter 11 bankruptcy in July. The company operates mines in West Virginia and Kentucky.

All three companies are based in St. Louis.

The lawsuit was filed this week in federal court in Charleston.