Rescue teams hunting for survivors have located the site where eight workers remain stuck in the mine shaft, but it is unclear if they are alive, the China News Service reported.
"We were preparing to evacuate when the explosion occurred, sending glass and rocks flying everywhere," miner Wang Xingang told China National Radio after Saturday´s blast at a mine near Hegang City in Heilongjiang province.
"We began running out and shouting to evacuate, smoke was everywhere, I couldn´t see at all, I was trying to feel my way out from my memory of the shaft."
The explosion occurred at 2:30 am Saturday (1830 GMT Friday) when a total of 528 miners were in the pit, according to a statement issued by the State Administration of Work Safety.
According to local news reports, the blast was felt as far away as 10 kilometres (six miles).
The accident was the deadliest in the energy-hungry nation since an explosion killed 105 miners in Shanxi province in December 2007.
With the main entrance blocked with debris, rescue teams equipped with oxygen tanks were entering the shaft through an adjacent mine, braving high gas levels to find survivors, media reports said.
"I was with a group of 10 miners (when we were told to evacuate), right now I don´t know if they made it out," mining veteran Fu Maofeng, 48, told the East Asia Trade News from his hospital bed.
Miners near the shaft entrance were told to evacuate after gas levels in the mine rose sharply, he told the paper.
When he and two others reached the entrance to report the rising gas levels, a huge blast ripped through the main shaft, he said.
The toll has more than doubled from 42 dead on Saturday, with 66 missing.
Rescue workers have identified 28 areas in the mine some 500 metres (1,650 feet) below ground where teams were working at the time of the blast, reports said.
Over 400 miners escaped, with more than 60 hospitalised with injuries.
"Most of the injured are suffering from compound injuries, like respiratory injuries, broken bones and gas poisoning," Pan Xiaowen, director of the Hegang general hospital, told the radio station.
"Currently six of the injured are in critical condition and the others are basically stable."
On Saturday, President Hu Jintao and Prime Minister Wen Jiabao issued orders to take all measures to rescue workers, while Vice Premier Zhang Dejiang was dispatched to the mine to oversee the operation, state media said.
The head and vice head of the mine, which is run by the Heilongjiang Longmay Mining Holding Group, and its chief engineer have been removed from their posts, the China News Service said.
The director of the work safety administration has been tasked with leading an investigation into the blast, it added.
According to the mining group´s website, the mine produces 1.45 million tonnes of coal a year and in 2009 ranked 12th out of China´s top 100 mining companies and seventh in terms of production volume.
China has a dismal work safety record, with thousands of people dying every year in mines, factories and on construction sites.
Its coal mines are among the most dangerous in the world, with safety standards often ignored in the quest for profits and the drive to meet surging demand for coal -- the source of about 70 percent of China´s energy.
The central government has campaigned in recent years to modernise its collieries and control the leakage of gas, particularly methane, a pollutant responsible for several mine explosions.
Official figures show that more than 3,200 workers died in collieries last year, but independent labour groups say the actual figure could be much higher, as many accidents are covered up in order to avoid costly mine shutdowns.
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