All 166 miners trapped underground in a coal mine gas blast, the worst mining case ever reported in China, were confirmed dead yesterday.

Recovery work and efforts to console the relatives of those killed in Sunday's disaster in Northwest China's Shaanxi Province started yesterday.

But as the mopping up work began, another gas explosion in Southwest China's Guizhou Province killed 13 and left three others missing.

The Shaanxi provincial government officially announced yesterday all the 166 miners trapped underground by the blast were dead, and recovery work goes on.

Early yesterday morning, the bodies of 21 of the 65 miners killed in the disaster at the Chenjiashan Coal Mine in Tongchuan of this northwestern province were found, while 101 miners remained missing in the gas-filled tunnel, local officials said.

Huo Shichang, director of Shaanxi Provincial Coal Industry Bureau, said the bodies were the first to be recovered from the mine.

"More than 200 rescuers have been sent down to look for the missing miners," the director said.

Experts who travelled to the area to take part in the rescue work and investigate the cause of the accident concluded that the miners trapped underground at the time of the accident had almost no hope of being alive.

Zhao Qingyun, an expert on gas and ventilation and deputy director of the Ventilation Office of Shanxi Yangquan Coal Industry Group, said the temperature may be as high as 1,000 to 2,000 C at the blast site.

"And the pressure there may be seven to 10 times normal atmospheric pressure, far more than people can withstand, so there is little hope that any of the missing miners have survived," Zhao said.

Experts said the Chenjiashan Coal Mine has a complicated geological structure with coal, oil and gas intergrowth. It is also a mine with high gas density which means disasters such flood, fire and gas explosion occur frequently.

"In the mine, the coal seam can spontaneously combust when the temperature reaches 33.6 C, and the explosion index of coal dust underground is 35.42 per cent, which explodes easily when coming into contact with fire," experts said.

According to a survey made on Tuesday by the rescuers, some 800 metres deep in the mine, the gas density was 9 per cent, very likely to cause explosion, and the density of carbon monoxide is 0.1 per cent, enough to kill people.

In order to avoid a new explosion and ensure the safety of recovery workers, rescue work had to be temporarily suspended yesterday and more efforts have been made to stop the fire and to improve ventilation, Huo said.

Wang Xianzheng, director of the National Safe Production Supervision and Administration Bureau, told a working conference held at the mine that the disaster was very complicated given the high density of gas and fires in the mine.

"Improving ventilation may reduce the gas density, but increase the risk of fire. While reducing ventilation may cut the risk of fire, but increase the density of gas."

Wang stressed that a balance must be maintained between ventilation and the gas and fire underground.

According to the regulations concerned, the relatives of the dead miners from poverty-stricken rural families will be helped by local civil affairs departments.

And because the Chenjiashan Coal Mine purchased the employer liability insurance, the Chinese People's Property Insurance Company has already paid 1.5 million yuan (US$180,000) to the accident-hit coal mine, Huo said.

A gas explosion that occurred in a coal mine of Southwest China's Guizhou Province yesterday morning led to 13 deaths and three missing, Xinhua reported.

The accident occurred at 1:30 am, when 49 miners were working at the No 2 pit of Shuomebei Coal Mine in Panxian County of Liupanshui. Thirty-three workers narrowly escaped and four were injured.

The bodies of 13 miners have already been found by the rescue team. Efforts are still being made to search for the three missing miners as we go to press.