BEAVER, W.Va. — The owner of the West Virginia coal mine where an explosion killed 29 men last year kept two sets of books on safety conditions — an accurate one for itself and a sanitized one for the government, federal regulators said Wednesday.

Managers at Massey Energy pressured workers at the Upper Big Branch mine to omit safety problems from the official set of reports, said Mine Safety and Health Administration official Kevin Stricklin. Workers told investigators that the company wanted to avoid scrutiny from inspectors and keep coal production running smoothly.

Massey was bought by rival Alpha Natural Resources earlier this month, and the new owner said it is looking into the allegations.

Even before the April 5, 2010, tragedy that was the nation’s deadliest coalfield disaster in four decades, Massey had a poor safety record and a reputation for putting coal profits first. The mine was cited for 600 violations in less than a year and a half before the blast.

In its previous briefings, Mine Safety and Health Administration blamed the explosion on naturally occurring methane gas and coal dust. It said poorly maintained cutting machinery sparked the blast and a malfunctioning water sprayer allowed a flare-up to become an inferno.

“Managers were aware that chronic hazardous conditions were not recorded,” Stricklin said. Testimony from some of the 266 people the administration interviewed “indicated that management pressured examiners to not record hazards” at Upper Big Branch.

So far, one Massey employee has been indicted. Security chief Hughie Stover was charged with lying to the FBI and the administration and obstructing justice by ordering thousands of pages of documents thrown out.

An independent investigation commissioned by former Gov. Joe Manchin accused Massey of allowing highly explosive coal dust and methane gas to accumulate.

No one should have been injured,” Stricklin said, “and definitely no one should have died.”