NEW YORK (Reuters) - The company that owned the coal mine where 29 miners died in the worst U.S. mining disaster in four decades concluded the explosion was the result of unpreventable natural gas buildup and not coal dust, contradicting the findings of an independent investigation.
Massey Energy's investigation of the Upper Big Branch mine blast in April 2010 also said the probe being carried out by the federal Mine Safety and Health Administration (MSHA) is "flawed."
The findings were released on Friday by former Massey Chairman Bobby Inman and came two days after Massey ceased to exist as an independent company following its $7 billion acquisition by Alpha Natural Resources.
Massey's report said it found the explosion at the mine in West Virginia was caused by "a massive inundation of natural gas."
It said the mine was adequately rock dusted prior to the explosion and that the mine's ventilation system did not contribute to the blast.
That contradicts the conclusion of an independent investigation released last month that laid the blame squarely with Massey for safety failings, including inadequate ventilation to prevent coal dust buildup.
A report by the Mine Safety and Health Administration on the accident has not yet been released.
Following the accident, 13 of the 29 families of the dead miners have sued the company for wrongful death and eight have agreed to settlement offers made by Massey.
As part of its deal to take over Massey, Alpha agreed to assume liability stemming from legal action.
In a letter with Massey's report, Inman wrote that the company's investigation was completed several weeks ago but that Alpha requested its release be delayed "to minimize any publicity" that could detract from the shareholder votes on the deal completed on Wednesday.
The Massey-Alpha deal was finalized after shareholders for both companies voted in favor of it.
Inman urged Congress to pass legislation to create an independent agency to investigate mine accidents similar to the National Transportation Safety Board, which investigates airline crashes, rather than let the Mine Safety and Health Administration "police itself."
The former Massey chairman said it was "unacceptable to expect MSHA to act as investigator, judge and jury when their direct actions or lack thereof may have contributed to accidents."
He also recommended that mine-safety regulations "be more aligned with scientific findings and updated technologies."
(Reporting by Steve James; Editing by Gary Hill)