"They were wearing breathing apparatus, so it did seem they were getting ready to go down past what appears to be a level of water in a kink in the mine," he said.

"There are also three boats, we've been told, that are down there in the mine shaft, so the possibility is that the water has retreated enough that they can get boats across the shaft."

The coal mine flooded on March 28 after miners digging tunnels broke into an abandoned shaft. State media said the shaft flooded with the equivalent of more than 55 Olympic swimming pools of water.

'Very difficult'

Rescuers and divers were able to partially enter the mine in the early afternoon on Saturday as the water level began to go down, but divers said the situation underground remains "very difficult".

"I think we should still believe in the miracle of life"

Dr He Xiuming

On Friday, tapping sounds were heard coming from within the mine, but no signs of life have been heard since then.

Despite the prolonged period underground, experts have said there could still be survivors, if the miners have access to uncontaminated air and water supplies.

"The main thing we are prepared to treat is exhaustion because they have been trapped for so long with no support or nutrition, no sunlight, air or water," Dr He Xiuming, on standby at the mine from a nearby hospital, said.

"I think we should still believe in the miracle of life. We have seen it in the Sichuan earthquake, the Indonesian tsunami, so we should try to be positive."

Early investigations by China's work safety administration found that the mine's managers ignored water leaks from the abandoned mine before the accident.

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

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