The owners of a mine in the West Papua province of Indonesia say rockfalls are hampering rescue efforts after last week's tunnell collapse, which has now killed at least eight workers.
Freeport McMoRan says hopes are fading of finding alive any of the 20 still missing.
Freeport closed the world's second largest copper mine on Wednesday, a day after a tunnel fell in on 38 workers undergoing training.
Several of the 10 rescued are still in hospital.
The company is using a device to detect vibrations to find out if any of those trapped are still alive, but says it has not had any signs of life in the last 72 hours.