Rescuers have found three more bodies in a coal mine in northeastern China hit by a massive gas blast, bringing the confirmed death toll to 107, a mine spokesperson and state media said on Wednesday.

The new toll makes Saturday's tragedy in the city of Hegang in northeastern China the deadliest reported accident in the country's disaster-prone mining industry for more than four years.

Officials had previously confirmed 104 people dead and four missing but a spokesperson for the majority state-owned Xinxing mine said two bodies were recovered early on Wednesday morning.

"We have found two of the missing people," spokesperson Zhang Jinguang told AFP.

State television later reported another body had been found, leaving just one more miner missing.

Officials had earlier expressed doubts that the missing miners could have survived, saying they had been working near the centre of the gas explosion.

The recovery of the three bodies makes the disaster the deadliest in China since 123 people were killed when a mine in southern Guangdong province flooded in August 2005.

Relatives of victims killed and hurt in Saturday's blast have angrily demanded answers about the disaster as officials said a preliminary probe pointed to poor management at the mine, one of China's oldest and largest.

Press reports have quoted Zhao Tiechui, deputy head of the state work safety agency, as saying the mine was overcrowded and insufficiently ventilated, contributing to the high toll as volatile gases built up in the mine and exploded.

The tragedy has re-ignited nationwide concerns over poor safety and working conditions in the country's mining sector, in which thousands of miners are reported killed each year in accidents.