Federal inspectors issued more than 130 citations at seven Kentucky underground coal mines during special safety inspections last month, the U.S. Mine Safety and Health Administration announced Wednesday.

At one mine, the Manalapan Mining Co. Inc.'s RB No. 12 Mine in Harlan County, inspectors found a number of problems, including that some detectors used to check for explosive methane gas were defective or had dead batteries, MSHA said in a news release.

MSHA began such "impact inspections" after an April 2010 explosion that killed 29 workers at a West Virginia mine.

The inspections target mines the agency says need more attention because of a history of compliance problems, a high number of accidents or other red flags.