Murray said the Illinois Basin market had been in good shape until the arrival of two companies that invested in low-cost longwall mines.

"When I built my two mines in [the Illinois Basin], things were in balance," he said.

"There wasn't room for another longwall mine, and another company built four, and another one is bringing one online."

Although Murray did not name the companies, state records show Foresight Energy has four longwall mines in the Illinois Basin and White Oak Resources is building one.

In his prepared comments, Murray delivered a speech about the regulatory challenges facing coal and discussed his purchase of five former Consol Energy coal mines in West Virginia's Northern Appalachian region.

He said the mines fitted into Murray Energy's business model, and the company won the bid for the mines after promising to look after Consol's legacy, even though it was not the highest bidder.

Murray said he intended to be the "last man standing”, increasing production despite the coal industry being “under assault.