TALLMANSVILLE (USA), Jan 3: Rescuers in the United States on Tuesday drilled into a coal mine where 13 miners have been trapped for more than 24 hours, but the company said it was ‘very discouraged’ by high levels of carbon monoxide detected.

Air quality tests showed more than three times the safe limit of carbon monoxide, said Ben Hatfield, chief executive of Ashland, Kentucky-based International Coal Group, which owns the Sago mine in central West Virginia.

“We are very discouraged by the results of this test,” Mr Hatfield told a news briefing.

He said a camera dropped into a part of the mine 76 metres below ground and almost three kilometres down the mine showed no survivors, but also no sign of substantial explosion damage.

“While we’re very disappointed by the information we have received thus far, we remain determined to continue the search so long as there is hope, and hope remains,” Hatfield said.

The next step was to deploy a robot to search farther inside the mine for the miners trapped since a blast at 1130 GMT on Monday.

Mr Hatfield, who spoke to reporters after briefing relatives of the miners gathered in a church, said there was hope that the miners would be in another location in the mine.

“All we know is that there was an explosion ... We do not know what the fuel source was,” he said.

The incident came four years after nine Pennsylvania coal miners were rescued in 2002 following a 77-hour ordeal in a flooded mine shaft 70 metres underground.

Thirteen people were killed in a Dec 2001 coal mining explosion in Brookwood, Alabama. In 1968, an explosion at a Farmington, West Virginia, mine, caused 78 deaths.

The company’s senior vice president, Gene Kitts, said earlier that nine of the 13 trapped miners had more than 30 years’ mining experience and the

average for the group was 23 years. —Reuters