A delegation of unions are calling foul on federal mine safety regulators who revoked a rule that required metal and hardrock mines to conduct safety inspections before miners go into the mines.

The United Steelworkers, AFL-CIO, and the United Mine Workers of America filed a petition for review May 2 in the U.S. Court of Appeals for the District of Columbia Circuit, contesting the rule that was finalized April 9.

The unions said the new rule will expose workers to potential roof collapses and other deadly mine hazards.

Phil Smith, director of government affairs...