Operations continued to save 28 trapped miners on Tuesday as two more bodies were recovered from a north Chinese mine, bringing the confirmed death toll after an explosion to 19.
"So far we have found 19 bodies, there are still 28 miners trapped," an official with the Jiaojiazhai mining bureau told the agency by phone.
"It is hard to say what their chances are, every time it is different."
Seventeen miners were reported dead when the explosion ripped through the state-owned mine, belonging to the Datong Coal Mine Group, in Shanxi province Sunday.
The cause of the blast was "human error", Xinhua news agency said.
Mine operators failed to follow regulations and evacuate the mine after a Sunday power outage led to the shutdown of the mine's ventilation system and the accumulation of deadly gases, the report said.
The blast occurred after electricity to the mine was restored, Xinhua added.
So far, some 90 rescuers in eight teams had descended 300 metres underground in search of the missing workers, but toxic fumes and a lack of oxygen in the mine were hampering operations, the report said.
"Yesterday (Monday), when we were carrying out rescue operations we heard no sounds to indicate they have survived," a rescue worker surnamed Wang said.
Mines in China -- which relies on coal for about 70 per cent of its power needs -- are regarded as the most dangerous in the world.
Almost 6,000 workers were killed in the country's industry last year -- a rate of about 16 fatalities each day -- according to official figures.
Labor rights groups say the real number of mining deaths could be as high as 20,000 a year, with the official tally much lower because local government officials and mine owners often cover up accidents.