Relatives of victims angrily demanded answers Monday as the death toll from China's worst mining disaster in two years climbed to 104 and hopes of finding more survivors faded.

Rescuers recovered 12 more bodies, a spokesman for the mine in the northeastern province of Heilongjiang said, leaving four miners still unaccounted for after Saturday's huge blast.

A preliminary investigation pointed to lax management at the state-run mine, according to Luo Lin, director of the State Work Safety Administration and head of a probe into the tragedy.

"The mine's safety responsibility system did not work, they were not checking earnestly enough for hidden dangers," Luo told state television.

"This accident was clearly linked to a lack of responsibility, we must seek those responsible for this in accordance with the law."

Rescuers braving toxic gases were pressing on with a desperate search of the Xingxing mine in the city of Hegang to try to locate the four men, said mine spokesman Zhang Jinguang.

"Rescue operations are still continuing. If we haven't found them yet we believe they are still alive," Zhang told AFP. "If there is any chance of finding them, we will not give up."

State television however quoted officials as saying the missing miners were believed to have been working near the centre of the explosion, the latest tragedy in the country's notoriously dangerous mining industry.

Smoke could still be seen on Monday billowing out of an entrance to the mine, one of the largest and oldest in China, as authorities turned to the task of dealing with grieving relatives.

Families of the dead miners would receive up to 300,000 yuan (44,000 dollars) in compensation, the China News Service said.

Zhang said psychologists were being brought in to help survivors and relatives of victims cope with the disaster, which also injured more than 60 people.

A group of women waited outside an entrance to the mine office in sub-zero temperatures, crying and shouting angrily in despair.

"I haven't had any news. My husband was only 42," wailed one woman, tears streaming down her face.

A second woman complained that her family had received no information about the fate of her younger brother.

"He was my little brother. It's been three days and still we haven't had any news," she cried.

AFP journalists also saw dozens of people shouting in what appeared to be a protest in Hegang but police cordoned off the crowds and prevented reporters from reaching them. Zhang said the gathering was unrelated to the disaster.

The accident was the worst in energy-hungry China since an explosion killed 105 miners in Shanxi province in December 2007, and has reignited concern over safety and working conditions in the country's mining sector.

Even as rescuers searched the Heilongjiang mine, state-run Xinhua news agency reported 11 workers had died and three were missing in a similar blast at a coal mine in central Hunan province on Sunday.

China's 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 the country's energy.

Despite a high-profile government campaign to shut down unsafe and illegal mines, hardly a week goes by in China without reports of deadly accidents.

Heilongjiang governor Li Zhanshu called for mine safety to be made a "top priority that we can hang our hearts on and grasp in our hands."

"We definitely cannot exchange the lives and blood of our workers to pursue GDP growth," Li said in remarks posted on the government's website.

The head, deputy head and chief engineer of the mine, which is run by the majority state-owned Heilongjiang Longmay Mining Holding Group, have been removed from their posts, the China News Service has reported.

Official figures show that more than 3,200 workers died in coal mines last year. But independent labour groups say many more deaths are covered up.