A gas blast at a coal mine in central China has killed 26 people, who were working despite an order to halt production at the site.

An official said on Wednesday that 20 other miners had managed to escape the mine in Henan province's Mianchi county when the gas explosion occurred a day earlier.

The cause of the blast was not yet known and a police investigation was under way, according to the official Xinhua news agency.

The mine had been closed for technical upgrades but the mine owner had ordered workers back into the shafts, Xinhua reported, citing Li Guoqi, deputy chief engineer at the mining company Yi Ma.

It said the owner had fled and police were looking for him.

The Juyuan Coal Industry Company mine was in the process of being merged into the state-owned Yi Ma Coal Industry Group.

In a separate accident on Tuesday, a coal mine tunnel in northeastern Liaoning province collapsed, leaving four miners dead, Xinhua said, citing local authorities.

China's notoriously dangerous coal mining sector is regularly hit by deadly floods, explosions and shaft collapses blamed on the flouting of safety rules as operators try to keep costs down.

Most accidents are blamed on a buildup of coal gas or methane ignited by sparks or open flames.

Last year 2,631 Chinese miners were killed, according to official statistics, but independent labour groups say the true figure is likely to be much higher as many accidents are believed to be covered up.

Source: Agencies