A worker crushed at the Stockton coal mine near Westport is in a serious but stable condition in hospital.
The man, in his early 40s, was working for a sub-contractor building a coal handling and processing plant, and is understood to have become trapped between two crates or containers about 11am on Tuesday.
He was treated by St John Ambulance staff before being flown to hospital in Greymouth by the Solid Energy rescue helicopter.
Solid Energy says details of the accident remain sketchy and the Department of Labour is investigating.
Stockton is New Zealand's largest open-cast coal mine.