Rescuers are moving slowly towards four workers who have been trapped underground in a wrecked gypsum mine in eastern China for 10 days, media reports have said.
China National Radio said the men are trapped more than 200m below the surface.
Because the ground is fragile, rescuers have managed to drill a path only 25m deep after more than 40 hours.
Rescuers using infrared cameras detected the survivors last Wednesday – five days after the cave-in.
At least one person was killed in the mine collapse in Shandong province on December 25.
Thirteen others are missing, and 11 made it to safety or were rescued earlier.
Rescuers initially believed they had found eight trapped survivors but have been able to make contact with only four.