Rescuers say it might be more than two weeks before they can bring to the surface a group of miners trapped hundreds of metres underground in the Hushan gold mine in Shangdong province.
An explosion on Jan 10 caused a massive collapse while the mine was under construction.
“The obstacles are just too huge, which means we need at least another 15 days or even more to reach the miners,” Gong Haitao, deputy head of the local publicity department, said.
If the rescue goes ahead as planned, the miners will have been trapped at least 600m underground for around four weeks.
From the group of 11 miners rescuers first made contact with last weekend, one has since died, according to the Xinhua News Agency.
Rescue teams have so far only managed to drill small holes but a communication line has been established and food and medicine is being lowered to the survivors down a narrow shaft.
They’ve been receiving porridge and nutritional liquids, and a few days ago asked for a traditional meal of sausages.
Currently, rescue workers are trying to widen the shaft to make it big enough to lift the miners out. However, drilling is proving difficult as drill bits need to cut through the particularly hard granite trapping the miners.
Rescuers face an added problem as the mine is water-logged and there is a real risk the chamber where the miners are trapped could flood.
Another 10 miners have not been heard from, despite rescuers lowering life detectors and food into other sections of the mine.
Hopes of a miraculous rescue are still generating an outpouring of sympathy and encouragement on the Chinese social media site Weibo.
Managers of the mine were detained after they failed to report the accident for more than a day.
Mining accidents are not uncommon in China, where industry safety regulations are poorly enforced.