Massey Energy, the company that owns the Upper Big Branch mine in West Virginia, where 29 miners died this month, defended its safety record Friday and promised that 'there will be accountability' if improper conduct took place. 'Clearly, something went wrong at Upper Big Branch, but we simply don't yet know what it was,' the company said in a news release. 'What we do know is this: Accusations that Massey Energy is indifferent to safety could not be more wrong. Our company puts the safety of its members first -- and always first.' The statement came in response to a New York Times article on Friday that detailed widespread problems in Massey mines cited in federal safety reports and by Upper Big Branch miners. The problems included a coal storage shaft known as a 'glory hole,' which the miners said was not properly sealed and had leaked methane gas. In their statement, Massey officials said that the shaft was filled and sealed according to a plan approved by federal regulators, and was regularly inspected. They also said that the mine used substantially more air and Massey miners received more training than is required by law. Federal regulators at the Mine Safety and Health Administration, however, have repeatedly found violations of ventilation and training requirements at Upper Big Branch and other Massey mines, one of the reasons the company leads the agency's nationwide list of troubled mines. Massey's announcement came as another coal miner died Friday after being pinned by a mining machine in the same county where the explosion occurred, at a mine owned by International Coal Group. The mine where the death occurred Friday was one of the 48 identified by federal regulators for greater scrutiny because the mines are deemed to have had repeated and serious violations. 