Officials told Xinhua news agency that the workers have only a slim chance of survival in the mine, in Xintai city 450km (280 miles) south of Beijing.

The agency reported that hundreds of troops and police were at the scene helping rescue teams.

China's coal mines are among the most dangerous in the world, with more than 5,000 deaths reported annually. Hopes were also fading for the survival of nine other miners, trapped in another mine nearby.

Describing the Xintai flood, local official Zhang Dekuan said: "There were 756 miners working under the ground when the accident occurred." Of these, 584 managed to escape from the pit, he said.

Xinhua reported that the mine, in eastern China's Shandong province, was overrun with surface water at about 14.30 local time (06.30 GMT) on Friday. The area was hit with about 205mm of rain, triggering flash floods and bursting the banks of the nearby Wen river.

Floodwater from the river swamped the coal mine via an old shaft. About 2,000 Chinese army troops, armed police and miners are trying to shore up the river's banks.