The eastern Kentucky coal mine where five men were killed in an explosion received several safety citations deemed "significant and substantial" less than two weeks before the blast, according to a published report.

Federal mine inspectors found an accumulation of loose coal and combustible dust up to 30 inches deep in some places at Kentucky Darby Mine No. 1, according to a Mine Safety and Health Administration report obtained by The Courier-Journal of Louisville on Thursday after filing a Freedom of Information Act request.

Click here to read the Courier-Journal story.

Agents reported other combustible material — including wooden pallets and open oil cans — near a conveyor belt. Inspectors also found broken water sprinkler systems and sections of the mine's roof that were not supported.

Two miners were killed in the explosion on May 20 and three others died of carbon monoxide poisoning. Investigators have not determined the cause of the accident.

Federal mine inspectors issued the four citations on May 9, finding the infractions "significant and substantial" and "reasonably likely" to cause injury or illness.

MSHA records show at least one of the areas where infractions were found was cleaned up by May 11.

In late May, the agency released a report detailing 11 additional citations issued at the mine on May 15 and 17. Some were deemed reasonably likely to lead to injury, including one for having combustible materials in sections of the mine in the form of "oil, oil-soaked fine coal and coal dust."

Butch Oldham, a United Mine Workers union international representative who took part in interviews with mine employees as part of MSHA's investigation into the accident, said having coal dust piles more than two-feet high is "excessive."

Darby officials and MSHA had no comment.