Treacherous conditions, including the presence of poisonous gas, slowed the effort to rescue 13 trapped coal miners yesterday, but rescuers still held out hope for a miracle to save the men.

"We still pray for miracles in West Virginia. We still believe in miracles," state Governor Joe Manchin told reporters at the coal mine. "We are hoping for that miracle."

There still had not been any communication with the miners, trapped since 6.30 a.m. (1130 GMT) on Monday.

At the White House, President George W. Bush said he had spoken to Gov. Manchin about the trapped miners. "I told him that Americans all across our country were praying for the miners who are trapped in the mine there in West Virginia," he said.

"I also assured him that the federal government will help the folks in West Virginia any way we can to bring those miners out of that mine, hopefully in good condition."

Rescuers drilling a second hole down into the Sago mine were being slowed by groundwater, said Ben Hatfield, president of International Coal Group Inc., which owns the mine in central West Virginia.

A first hole was drilled some 76 metres down and almost three kilometres into the mine revealed more than three times the safe limit of carbon monoxide, a colourless, nearly odourless gas.

Mr Hatfield told an earlier news briefing, "We are very discouraged by the results of this test."

A camera dropped down that hole showed no survivors, but also no sign of substantial explosion damage meaning noxious gasses were the biggest threat to any of the stranded miners who may still be alive.

"The impact of the carbon monoxide is the greatest danger," Mr Hatfield said. He said workers were drilling a third hole into an area where it is hoped the miners sought refuge. "Progress has been slow," said Mr Hatfield.

He said rescue workers were speeding up their search, advancing past mechanical robots that had been used earlier but became bogged down in mud.

He said rescuers had reached around 10,200 feet inside the mine so far. "We don't know exactly where the crew is but it's somewhere between 11,000 and 13,000 feet."

The cause of the blast was still not known.

The incident came four years after nine Pennsylvania coal miners were rescued following a 77-hour ordeal in a flooded mine shaft 240 feet underground.

The mine company's senior vice president, Gene Kitts, said that nine of the 13 trapped miners had more than 30 years' mining experience and the average for the group was 23 years.

"This is not a rookie crew underground," he said. "So we're just trusting that their training and their mining instincts have kicked in immediately and they've taken every step possible to put themselves out of harm's way."

Hundreds of family and friends gathered at a nearby Baptist church where the Red Cross had set up operations.

Nick Helms, son of trapped miner Terry Helms, held out hope his father would find a way to survive. "My dad is a smart guy," he said. "I have faith. I don't go to church a lot but I believe and we're keeping the faith."

The explosion happened when the mine was reopening after being closed for the holidays, said Gov. Manchin's spokesman Lara Ramsburg.