The first phase of the Royal Commission investigating the Pike River mine disaster is due to start in Greymouth next week, with evidence from 12 witnesses.
Twenty-nine men died in a series of explosions at the West Coast coal mine in November last year.
The first of four phases of inquiry will look into New Zealand's mining laws and regulations, and the geography, approval and design of the Pike River mine, the Royal Commission says.
The witnesses will include the chief executive of Pike River Coal Ltd at the time of the disaster, other mining companies, experts, representatives of government departments and the regional council.
Other phases of the inquiry will investigate the search and rescue processes, what happened on the day of the initial explosions and national mining policies.
There is no set end date for the inquiry, but phase one is due to be completed by mid-July.