By Jon Hurdle
MONTCOAL, West Virginia (Reuters) - Dangerous gases forced rescue teams to retreat from their search on Thursday for four miners missing in a West Virginia coal mine since a massive explosion killed 25 of their colleagues.
"We've had a setback," said Kevin Stricklin of the U.S. Mine Safety and Health Administration at a news briefing.
Teams of rescuers began the gruelling 5-mile (8-km) underground trip at about 5 a.m., hoping to find survivors in one of the refuge chambers in the Upper Big Branch mine that are stocked with food, water and air.
But a build-up of noxious gases inside the mine was so high that a second explosion was possible, and the rescuers were retreating, Governor Joe Manchin said.
"Unfortunately we have the worst scenario," he said. "The quality of air has deteriorated."
Reaching one of the refuge chambers is the only way any of the four missing miners could have survived Monday's "very violent explosion," Manchin said.
The blast at the Massey Energy mine about 30 miles (48 km) south of the state capital Charleston caused the deadliest U.S. mine disaster since 1984. Eighteen bodies remain in the mine.
Rescue teams could be sent back in but not until the mine is cleared of the dangerous gases, Stricklin said.
"They are in danger, and that is the intent of evacuating the mine," he said. "They're en route coming out of the mine right now."
The setback marks the second time rescuers were driven out of the mine by the build-up of dangerous gases. Earlier teams were forced back on Monday, just hours after the blast.
Crews have been drilling boreholes in an effort to vent the mine of carbon monoxide and methane, but the layout of the mine makes the situation complicated, Stricklin said.
"It's kind of like we are blowing air into a pop bottle. There is nowhere for it to go," he said.
CAUSE UNDETERMINED
Shares of Massey, the largest coal producer in the Central Appalachia mountain region, were up about 1 percent in early trading on the New York Stock Exchange after losing more than 10 percent since the accident. Analysts predict long-term financial health for the company.
The cause of the explosion has not been determined but the build-up of combustible methane gas is often cited in mine blasts. Questions also have been raised about Massey's safety record and laws governing the mining industry.
Massey Energy has defended its safety record, saying its accident rate hit an all-time low in 2009.
The Upper Big Branch mine had three fatalities since 1998 and a worse-than-average injury rate in the past 10 years, according to federal records, which also show it has been cited for more than 100 safety violations already this year.
The company was cited for two mine safety violations on Monday, which Stricklin said were not related to the disaster.
The Upper Branch mine blast is the nation's deadliest mining disaster since 27 miners died in a fire in Utah in 1984. West Virginia was home to the worst U.S. coal mine disaster, when 362 miners died at the Monongah mine in 1906.
(Writing by Ellen Wulfhorst; Editing by Mark Egan and Paul Simao)
