The bodies of all the miners trapped on May 18 in Zuoyun county in the northern province of Shanxi had been found by Wednesday, Xinhua new agency said.

Wednesday's gas blast also injured 37 in a colliery owned by the Fuxin Mining Group in the northeastern province of Liaoning, Xinhua said, adding four were missing.

"The explosion happened when workers were changing shifts. The exact number of people underground needs to be checked further," Wang Daguang, a local official, was quoted as saying.

The state-run Fuxin group's Sunjiawan mine was hit by China's worst coal mine disaster in decades when a gas blast killed 214 people in February 2005.

The world's deadliest mining industry is struggling to meet booming demand and high prices for coal -- which fuels about 70 percent of China's energy consumption.

In the rush for profits, safety regulations are often ignored, production is pushed beyond limits and dangerous mines that have been shut down are reopened illegally.

Last year, 3,300 coal mine blasts, floods and other accidents killed nearly 6,000 people, according to official figures.

A court on Tuesday jailed six managers of a coal mine in far-west Xinjiang region to up to six years for failing to prevent a gas blast last July that killed 83 people, Xinhua said.

The sentences came as authorities considered amending the Criminal Code to raise the maximum jail term of 7 years for those responsible for work safety accidents, Xinhua said.