Richard Stickler, an acting assistant secretary of labor in charge of the Mine Safety and Health Administration, said the operator of the Crandall Canyon Mine showed "reckless disregard for safety," the Deseret Morning News reported. A spokeswoman for U.S. Attorney Brett Tolman said an investigation is already under way.

Nine men were killed at the mine in August 2007. Six coal miners were trapped in an initial collapse, and three more men, including two MSHA employees, died in a rescue attempt.

Kevin Anderson, a lawyer for Genwal Resources, accused the federal agency of trying to distract attention from its own shortcomings. He called Stickler's statement "reckless, irresponsible and without factual basis."