The injured mineworker was a member of a team installing roof supports in a recently formed underground tunnel area when the incident occurred at about 2am on Wednesday morning, Solid Energy said in a statement.

It said the worker was treated at Christchurch Hospital.

“The incident is still being investigated but it appears a lump of coal fell to the floor nearby and knocked him down as it toppled over,” Solid Energy said.

Following notification, inspectors from the Ministry of Business, Innovation & Employment’s High Hazards Unit visited the mine and issued a prohibition notice after inspecting the work area and discussions with mine management and members of the underground workforce.

Solid Energy group manager coal operations Larry Hull said: “We’re obviously very concerned that one of our people has been hurt. Prior to the inspectors’ decision the mine’s management team had already ceased underground face operations and had begun a risk assessment and review of all relevant operating procedures and job safety checklists.

“If any changes are needed as a result of those reviews, the underground mining teams and supervisors will take part in refresher training before work resumes.”

A protracted development phase for Spring Creek contributed to an 8% plunge in production for Solid Energy in the June quarter to 936,000 tonnes.

Production at Spring Creek mine for the year was down 40% at 240,000t with last coal being extracted in January 2012 as the mine develops the next five-year extraction block.