Published: Apr 26, 2010 8:52 PM EDT

CHARLESTON, W.Va. - Air samples did not show high levels of explosive gases just before an explosion in a West Virginia coal mine that killed 29 workers, the mine's owner said Monday. Massey Energy Co. board director Stanley Suboleski said the samples were taken by a foreman as part of a shift change exam of the mine. The examination also showed that air flow in the Upper Big Branch mine was fine.

Suboleski said all indications were that "at the start of the shift, everything was OK." The explosion occurred in the late afternoon of April 5. Two other miners were injured in the explosion at the Upper Big Branch mine. Massey held a news conference Monday to address several issues related to the explosion.

The news conference was held a day after President Barack Obama, Vice President Joe Biden and Gov. Joe Manchin led a memorial for the fallen miners. Massey Board Director Bobby Inman called allegations that the company put profits over safety a "big lie." He blamed such sentiment on the United Mine Workers' leaders and plaintiffs lawyers.

Massey is facing a shareholder lawsuit stemming from the explosion, as well as wrongful death litigation and mounting scrutiny from regulators.

Investigators have detected high levels of two potentially explosive gases inside the mine, and it could be a month before investigators can get inside to determine what caused the blast. Federal regulators have identified highly explosive methane gas, coal dust or a mixture of the two as the likely cause of the blast, but the ignition source is unknown.

The explosion will be the subject of a Senate hearing on Tuesday, with the nation's top mine safety official expected to testify. Obama has ordered a broad review of coal mines with poor safety records and urged federal officials to strengthen laws.

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