An early-morning explosion at a West Virginia coal mine yesterday trapped at least 12 miners 1.6 kilometres underground and officials said dangerously high levels of methane gas hampered the rescue effort.

Six miners escaped immediately after the blast at the Sago mine near Buckhannon, West Virginia, which was reported at about 8 a.m., said Louise Bleigh of the Upshur County operations office in Tallmansville.

She said 13 miners remained trapped. Terry Farley, an administrator at the West Virginia Office of Miners' Health Safety, put the number at "approximately 12".

High levels of methane gas around the mine forced officials to evacuate people from the area around the mine while they used fans to dissipate the gas, according to Steve Milligan of the county's Office of Emergency Management.

But Mr Milligan told CNN it was unclear whether the gas caused the explosion. "We don't know for sure," he said.

He said rescuers needed to clear the mine shafts of gas before they could move back in.

"There's been no contact with the miners at all," he said.

Rescuers from state and federal safety agencies were on site and more were en route, according to Mr Farley.

Residents said the blast shook nearby houses, according to local media that reported rescuers had not been able to establish communication with the trapped miners.

The mine, owned by International Coal Group Inc, is located in central West Virginia, about 160 kilometres from Charleston.

International Coal representative Mark Spencer said, "We have no comment at this time."

The West Virginia Office of Miners' Health Safety and Training says there were three fatalities involving miners in 2005 from three separate incidents.

In 2002, nine Pennsylvania coal miners were rescued after a 77-hour ordeal in a flooded mine shaft 73 metres underground.