BECKLEY, W.Va. — An independent investigation concludes the West Virginia coal mine explosion that killed 29 men last year was the result of safety failings by owner Massey Energy and rejects the company’s argument that a sudden gas buildup caused the deadliest U.S. coalfield disaster since 1970.

The report released this morning and commissioned by the state’s former governor said Massey violated basic safety practices, including not ventilating the tunnels enough.

The study supported the federal government’s theory that methane gas mixed with huge volumes of explosive coal dust turned a small fireball into a preventable earth-shattering explosion

“The disaster at Upper Big Branch was manmade and could have been prevented had Massey Energy followed basic, well-tested and historically proven safety procedures,” investigators wrote.

Virginia-based Massey did not immediately respond. It is being acquired by Alpha Natural Resources.