The Labor Department’s Mine Safety and Health Administration said Thursday it has ordered six coal mines in Kentucky to close after an “inspection blitz” last month.

Orders against five of the mines have been terminated and two operations have been sued by the federal government for providing advance notice of the inspectors’ presence on the properties, MSHA said.

The agency said April 21 that it initiated the inspections at 57 coal mines with a history of underground violations that could lead to an explosion.

The sweep came just weeks after the worst coal mining disaster in 40 years at Massey Energy Co.’s Upper Big Branch operation.

D&C Mining Corp., Left Fork Mining Co., Manalapan Mining Co., Conshor Mining, Red Bird Coal Co. and Cawood Enterprises are the operators whose mines were ordered to close.