The Royal Commission into the Pike River Coal mine disaster has for the first time confirmed it has used its power to force people to co-operate with the inquiry.
Twenty-nine men died in explosions at the West Coast mine which began on 19 November last year. Pike River Coal Ltd was put in receivership in December.
Pike River contractors and suppliers are owed $5 million. The group has formally told the commission its members will not appear before it due to a lack of funding for legal representation.
Contractors say they have vital evidence to present, but fear it may later be used against them.
The commission cannot compel people to appear, but confirmed on Wednesday that for the first time it has exercised that power.
It will not disclose exactly who has been compelled to co-operate, but says that may emerge during public hearings.
The commission will also not confirm whether it will force the contractors to take part, saying that would be a last resort.
The commission believes lawyers are not necessarily needed, saying the inquiry is different to a conventional court case and much of the evidence to date has been provided without legal assistance.
It says only some of the evidence will require further scrutiny at a public hearing and it has three lawyers on hand to help in that case.
But Christchurch lawyer Grant Cameron, who has experience with Royal Commissions, says it is common sense that the contractors should be legally represented during hearings into the mine disaster.