China mine rescue: Slow progress to reach Shandong survivors
Rescuers have been making slow progress in their attempt to reach survivors trapped in a gypsum mine in China, after it collapsed on Christmas Day.
Authorities have revised down the number of survivors who made contact with rescue teams on Wednesday.
State broadcaster CCTV reported officials saying there are now four instead of eight known survivors. They are among 17 left inside the mine.
Reports say 11 others have been rescued and one is known to have died.
The BBC's Stephen Evans in Beijing says rescuers have started boring a tunnel down to the trapped miners, and water and liquids have been passed down through a narrower bore-hole.
But the authorities in Shandong province where the accident happened are warning that the geology is difficult and progress will be slow, with continuing rock falls and unpredictable torrents of water underground, according to our correspondent.
It is not clear whether the four survivors who now cannot be located are still alive or dead.
The mine collapse in the town of Pingyi on the morning of 25 December was so violent that it registered at China's earthquake monitoring centre.
Rescuers first made contact with survivors on Wednesday, when they used infrared cameras to peer into darkness at the wrecked mine. The cameras detected the surviving miners waving their hands.
The workers were weak with hunger but otherwise were in good health, state media reported. The workers told rescuers they were in passages underground that were intact.
News outlet The Paper reported on Wednesday that police had enacted "enforcement measures" against several bosses at Yurong company which owns the mine, while local party officials had been sacked.
The company chairman Ma Congbo drowned himself by jumping into a mine well early on Sunday.
His motive was not clear but the Chinese authorities have hardened punishment of employers who are seen to be negligent.
China has a long history of industrial accidents. This incident came days after a landslide caused by construction waste in southern China left dozens of people missing and presumed dead.
The nation's mines have long been the world's deadliest, but safety improvements have reduced deaths in recent years.
Gypsum is a soft sulphate mineral that is used in building and construction.
Last year, 931 people were killed in mine accidents throughout China, significantly fewer than in 2002, when nearly 7,000 miners were killed.