The blast occurred at 8.26pm yesterday at the Xintai coal mine near the city of Yan’an, state broadcaster CCTV said, citing the municipal emergency management bureau.

Some 90 people were in the mine at the time of the explosion, nine of whom were trapped inside and were “found with no vital signs” by 9am today, according to CCTV.

Two others who made it to the surface “were seriously injured and died after resuscitation efforts failed”, the broadcaster said.

It went on to say a further 11 people were “lightly injured” and had been taken to hospital for treatment, adding that “their vital signs are stable”.

“The cause of the accident is currently under investigation,” CCTV said.

Mine safety in China has improved in recent decades, as has media coverage of major incidents, many of which were once overlooked.

However, accidents still occur frequently in an industry whose safety protocols are often lax, especially at the most rudimentary sites.

In February, a coal mine collapse in the northern Inner Mongolia region left dozens of people and vehicles buried under a mountain of debris.

Authorities did not disclose the final death toll for months, only saying in June that 53 people had perished in the accident.