Survival supplies could reach six trapped coal miners within two days as rescue drilling operations continue in Utah.
Robert Murray, one of the owners of the Crandall Canyon coal mine, said Wednesday that he still expects it to take a week or more for rescue personnel to reach the trapped miners. They are believed to be more than 450 meters underground and some 600 meters from the closest outside access point.
But Murray said smaller tunnels meant to establish communication with the miners and provide supplies could be finished Friday.
A spokesman said President Bush talked by telephone with Utah Governor Jon Huntsman to offer continued federal support for the mine rescue effort.
Tuesday, Murray said rescuers were back to "square one" after a new collapse forced rescuers to retreat from the mine, losing all the distance they had gained.
The Mexican consulate in Salt Lake City has confirmed that three of the trapped miners are Mexican citizens, although it has not released their names.
It is not clear what caused the mine to collapse. Scientists measured seismic activity in the area at the time of the cave-in, but it is unclear whether that data reflects an earthquake or the initial collapse of the mine itself. Murray insists the mine collapse was triggered by an earthquake.
Some information for this report was provided by AFP, AP and Reuters.