The Xinhua news agency reported on Thursday that there was little hope left of finding any more workers alive. The blast occurred on Wednesday evening at the Daping mine in central Henan province, where some 450 miners workers.
The deputy director of the state administration of work safety, Sun Huashan, said although he was pessimistic about finding any more survivors, search and rescue teams were continuing their work.
"So far, 56 people have been confirmed dead, but a detailed casualty list is unavailable. The rescue work is still going on," he said. The cause of the blast is under investigation.
The Daping mine employs some 4100 workers who hail from 33 counties largely in the province of Henan, Anhui, Shandong and Sichuan.
China loses some 7000 miners a
year to accidents and explosions
The accident is yet another blow to China's beleaguered coal mining industry.
China is the biggest consumer and producer of coal but appalling safety standards contribute to thousands of mining deaths each year.
Grieving relatives outside the Daping mine said workers had complained of safety standards in the mine.
Official figures say some 7000 people die each year in mine accidents in China. But independent experts say the actual figure is three times that number since officials suppress many deaths.
Meanwhile, in another accident in south-western China, six miners have died from a gas leak in the Chongqing municipality. The explosion killed six miners and left seven missing, Xinhua said.
The government has fumbled for ways to reduce the toll from mining accidents, vowing to close small-scale, unsafe, illegal mines and to raise safety standards.
However, it has had trouble keeping illegal and dangerous mines closed because the lure of profits has led many small mine operations and local officials to quietly re-open dangerous pits.