Six miners remained trapped deep in a collapsed mine in Utah last night as frustrated rescuers said it could take up to a week to reach the men - if they are still alive - and even longer to get them out.
No contact has been made with the miners, stranded 475 metres below the surface, in the 36 hours since the Crandall Canyon Mine caved in on Monday.
Officials say the six men could survive for weeks in an underground chamber.
A bitter dispute erupted over the cause of the accident, with the mine's owner insisting an earthquake was responsible after geologists had said seismic activity detected at the same time was probably caused by the cave-in itself.
Rescue crews were forced to retreat from what was seen as the fastest way to reach the miners, using an abandoned mine shaft, after falling rock made it too dangerous, and had moved only some 100 metres closer since the cave-in.
Early in the day, Bob Murray, president and chief executive of Murray Energy Corp, said it could take three days to reach the men. But he extended the timeline to one week after scant progress yesterday.