LOUISVILLE, Ky. (AP) _ A coal mine where three men were killed was operating without an approved ventilation system, a violation of federal mining regulations, says a federal official.

U.S. Mine Safety and Health Administration agency spokesman John McGrath said Monday in Washington that one of the men who died, Reed McKiddy, 21, who is listed as owner and operator of the R&R Coal Co. mine, was cited July 11 for operating the mine without approval.

Before a coal mine begins operating, federal regulations require the operator to submit plans showing how it will be ventilated.

McKiddy, Robert Bauer, 21 and Randy Powers, 18, were taken from the mine last Thursday and pronounced dead at Southeastern Kentucky Baptist Hospital. Ricky Bauer, 22, was treated at the University of Tennessee hospital in Knoxville for carbon monoxide poisoning and released.

Later the day he died, McKiddy was scheduled to meet with MSHA's district manager to discuss the ventilation plans, McGrath said.

Initial investigations by state and federal agencies show that poor ventilation was the likely cause of the deaths, officials said.

State investigators concluded their inspection of the mine Monday, said Faith Miller Cole, a spokeswoman for the Department of Mines and Minerals.

Investigators plan to interview Bauer before filing a report, she said.