"There's also a boat on stand-by. If the water comes down enough, they might as well use that to get across this area of water."

Medics wait

He said that medics were on stand-by to treat any survivors.

"We've been told 153 doctors and 153 nurses will all be sent here in the next hours," Fawcett said.

"That means one medical team for each of the miners trapped in the mine. It's a huge effort and a really public effort."

Rescuers and relatives of the trapped miners were getting a glimpse of hope on Friday, when a faint response to knocking on pipes running into the shaft was heard.

But there have been no further signs of life since then, state television said.

Glucose and milk was lowered into the mine after the tapping sound was heard.

Rescuers also sent down pens, paper and a telephone in attempts to communicate with the miners but did not get any response.

Thousands of workers have been tasked with pumping water out of the mine since it was flooded on Sunday.

Some miners who managed to escape told the Reuters news agency that the number of trapped miners given by authorities was too low and that nearly 450 people could have been underground at the time of the flood.

Deadly mines

China's coal mines are the world's deadliest, despite government efforts to reduce fatalities.

China's coal mines are the world's deadliest, despite efforts to reduce fatalities [Reuters]

Most accidents are blamed on failure to follow safety rules or lack of required ventilation, fire controls and equipment.

Accidents killed 2,631 coal miners in China last year, down from 6,995 deaths in 2002, the most dangerous year on record, according to the State Administration of Coal Mine Safety.

David Faikurt, a mine safety expert and adviser to the Chinese government and coal industry, said the government had introduced regulations in an effort to help reduce the frequency of accidents.

"Every mining company, once they build a new mine, must have a risk assessment plan before they even start digging the hole," he told Al Jazeera from Beijing on Friday.

"One of the problems is that this is a bit of a desk exercise," said Faikurt. 

"There is not a system in place which carries out a risk assessment on a daily basis, so that every miner, on every shift, and every supervisor, can be part of it and can be alert for the kind of situation that developed [at Wangjialing]."