The official Beijing Morning News said more than 40 miners were trapped inside the mine when the blast occurred early on Friday. Fifteen were rescued unharmed.

Officials said that the Yakeshi mine, about 1,000 kilometres (600 miles) northeast of Beijing, was government-owned and had operated legally since 1985.

Chinese coal mines have the worst safety record in the world. Official figures indicate more than 5,000 people were killed last year alone, while other estimates suggest the figure could be much higher.

Such explosions are usually caused by the accidental ignition of gas that seeps from the coal and builds up due to poor ventilation.

In May, more than 70 people died in a gas explosion at a mine in eastern China.

Many such incidents occur in privately owned mines, which lack operating licences and adequate safety equipment.

China relies heavily on the coal industry for its energy needs.