Despite rescue efforts, the bodies of six miners remain entombed in the mine since an August 2007 collapse in Emery County. Days after the accident, three rescuers died while trying to dig out the men.

According to a summary from Kennedy's office of the report, which is extremely technical in nature, the committee found that Murray Energy and its technical consultant, Agapito Associates, ignored the history of the mine's instability and did not make the right engineering assumption for the mine, while MSHA missed flaws in Agapito's analysis and did not submit plans to the agency's technical staff for review. The report says Murray Energy "ignored substantial evidence of instability during mining operation" and continued to mine for coal even in light of evidence there was danger near the north barrier, among several other conclusions.

"It is disheartening to see how much knowledge the company had prior to the accidents and that they disregarded warning signs," Havas said, referring to several "red flags" Kennedy highlights in the report. "They should have recognized there were very clear signals."

United Mine Workers of America International President Cecil E. Roberts said the report "underscores the need for the enhanced mine safety and health protections."

The House approved a mine-safety bill in January aimed at building on reforms approved by Congress in 2006, although there were some objections to the bill with critics saying the 2006 reforms haven't been given enough of a chance to be implemented yet. Kennedy has his reform proposal, the Miner Health and Safety Enhancement Act of 2007, that he introduced in June and aims to mark-up this year.

In light of the report, Roberts urged the committee to move forward on the bill.

"American coal miners are still dying just because they went to work. We need the enhanced protections the S-MINER Act provides. The terrible events at Crandall Canyon must never be forgotten and never be repeated."

MSHA reminded Kennedy that the official investigation into the accident is still taking place.

"MSHA's Accident Investigation Team is preparing the official investigative report that will determine the root causes of this accident as well as the appropriate enforcement actions, including any criminal referrals," MSHA spokesman Matthew Faraci said via e-mail. "Until the MSHA Accident Report and the DOL Internal Review are concluded, speculation by Senator Kennedy's staff is inappropriate."

Michael O. McKown, general counsel of UtahAmerican Energy, Inc., a subsidy of Murray Energy that operates the mine, said the report "is politically motivated, irresponsible and unjustifiable."