The Department of Labour is contracting an international mining expert to investigate the safety of all underground coal mines in New Zealand, Prime Minister John Key says.
The Cabinet on Monday agreed to establish a Royal Commission on the Pike River Coal mine tragedy in which 29 workers died after explosions at the West Coast mine from 19 November.
Police, the Coroner, Pike River Coal and the Department of Labour will also conduct inquiries.
Mr Key says all underground coal mines will be investigated but does not expect mines other than Pike River Coal to suspend operations during the investigation.
The state-owned company, Solid Energy, operates three; Huntly East, the Terrace Mine at Reefton and the Spring Creek Mine in Greymouth. The fourth, Roa Mine, is operated by Francis Mining and is also in Greymouth.