According to the Xinhua news agency on Wednesday, a total of 49 miners were working underground when the blast occurred.

Four of the 33 miners who managed to escape were injured.

The accident comes as China is still reeling from its worst coal mining disaster in recent history, with 166 workers killed after a gas explosion at a mine in Shaanxi province on Sunday.
  
More than 7000 workers die each year in China's coal mines, considered the world's most dangerous, according to official figures. 

'Stuck inside'

Meanwhile, about 800 angry miners' relatives rioted outside a government office in Shaanxi, protesting against the terrible safety standards.

Yan Mangxue, a Communist Party secretary at one of the villages where some of Sunday's 166 victims came from, said people were feeling very frustrated.

"They're very angry. They haven't seen their loved ones dead or alive. They're demanding government officials come out and give them answers.

"Several of us are stuck inside the building. The situation is very dangerous," Yan added.

Government officials confirmed fears on Wednesday that there was no hope of finding any of the 166 miners alive, three days after a blast tore through the Chenjiashan Coal Mine in Tongchuan city, Shaanxi province, on Sunday. 

Only 65 bodies have been retrieved from the shaft.