The country's top work safety official has blamed poor management and inadequate safety precautions for Saturday's mine blast in Heilongjiang province that claimed at least 104 lives.

The gas blast - the country's deadliest mine accident for more than two years - shook the State-run Xinxing Coal Mine, Longmei Group, at 2:30 am. At the time, 528 workers were underground. Xinhua News Agency reported that 420 employees escaped the blast.

As of last night, four workers were still missing and presumed dead.

Luo Lin, head of the State Administration of Work Safety (SAWS) and chief of the State Council probe team, yesterday said the accident in Hegang city started with a gas leak in one of the shafts. As a result of poor ventilation, gas quickly filled the main tunnel and the resulting blast shook 28 of the 30 mining platforms in operation.

While stressing that the exact cause of the tragedy had not been determined, Luo said the accident clearly suggests negligence and said it "has again revealed many problems in colliery management - it's a lesson we must all learn".

As a result of efforts to upgrade the coal sector, which is the major source of China's energy, thousands of small and often illegally operated collieries have been shut down in recent years. The overhaul of the industry helped drastically reduce the death toll, from almost 6,000 in 2005 to 3,200 last year.

But, despite driving several small, often poorly managed, mines out of business, disasters have flared at large State-owned collieries in recent years. Deficiencies in management and supervision, rather than lack of safety standards, have often been blamed.

In the February blast at the Tunlan mine in Shanxi, the presence of advanced equipment and a clean safety record were not enough to protect workers. That tragedy happened because none of the mine's alarms sounded and because nobody took action in the control room, despite indicators measuring dangerous levels of gas.

In the Xinxing mine accident, staff in the control room are understood to have received alerts notifying them about a sudden rise in underground gas levels at 1:37 am - 53 minutes before the tragedy.

Local authorities said all personnel were immediately told to evacuate the mine.

So far, no reason has been given to explain why more than 100 miners were still underground at the time of the blast.

Zhang Jinguang, publicity chief of the Hegang subsidiary of Longmei Group, yesterday insisted the evacuation of the mine was "timely".

"The evacuation took time and the miners had to run a long way from their mining platforms to the surface," he said.

A mineworker stands near a gas explosion site at the Xinxing Coal Mine in Hegang, Heilongjiang Province November 23, 2009. [Agencies]

Inadequate precautions and poor ventilation appeared to be among the failures, said Zhao Tiechui, deputy head of SAWS.

"The mine had too many mining platforms in operation and had sent too many workers down to increase output," Zhao said on Sunday. "Its underground structure was far too complicated for the mine's ventilation system to work effectively."

In the aftermath of Saturday's explosion, the mine's director, deputy director and its chief engineer were all removed from their posts. Zhu Haizhou, former deputy chief engineer at the local subsidiary of the Heilongjiang Longmei Mining Holding Group, was named the mine's new boss.

Heilongjiang Governor Li Zhanshu has said he takes responsibility for the accident.

"Development is the top priority, but gross domestic product cannot be traded for the lives and blood of employees," Li said.

The bodies of the miners were taken to a morgue 6 km east of Hegang where sobbing relatives gathered. Some family members and friends of the dead miners protested yesterday. They called on the mine's bosses to provide more details about what happened. Some of the protesters were taken inside the mine compound while others were driven away by the company's security.

The families of each deceased miner are likely to receive at least 250,000 yuan ($36,600). The payout is 25 percent more than the standard compensation offered following deaths caused by negligence.

A clause in the compensation agreement says families that hold funerals within 24 hours of signing the document will receive an additional 30,000 yuan. Those who do so within 48 hours will get 20,000 yuan, and people who wait another 24 hours will receive 10,000 yuan on top of the negotiated compensation.

Zhang, the mine spokesman, refused to say why families were being encouraged to move quickly to bury the dead.