A Royal Commission of Inquiry into the Pike River mining disaster would demonstrate to families of those killed how seriously it was being taken, Prime Minister John Key says.
Speaking on the TVNZ programme Question and Answer this morning Mr Key said Cabinet would tomorrow consider his proposal for the high level inquiry.
"I think it's a demonstration to the 29 families that we are taking this inquiry absolutely seriously, that we are determined to get answers for those families and that we will leave no stone unturned," he said.
"So I think a Royal Commission of Inquiry does give the gravitas and does demonstrate the significance of this national tragedy."
The commission would be chaired by a judge -- Mr Key had a person in mind -- and there would be two other members, one possibly an international expert. Tomorrow Cabinet would also consider terms of reference.
"That Royal Commission then draws on a great deal of international expertise, domestic expertise and knowledge, has very wide-ranging powers, absolute powers, to subpoena witnesses, to gather information, to ask questions."
Mr Key expected the inquiry to cover both why the accident happened and the response to it.
"... hard questions have to be asked and answered. Because in the end, the future of Pike River and actually underground coal mining in New Zealand rests on this. We can't put people into environments that are dangerous.
"We can put people into an environment where there is an element of risk - at the end of the day, lots of jobs in New Zealand have an element of risk. If you're a builder or an electrician you have an element of risk in your job. But there's a difference between risk which is managed and mitigated and a dangerous environment."
There were four underground coal mines involving 450 workers.
Alongside the Royal Commission, police, the Coroner's office, Department of Labour and the mine would carry out their own inquiries.
It was possible police would lay charges; "you can't rule that out", Mr Key said.
He did not expect any issues of ministerial responsibility given ministers, had followed advice.
Mr Key doubted the mine would reopen before safety questions were answered and probably not until after the Royal Commission of Inquiry was over.
The Prime Minister said safety had not been a consideration when the Government looked at proposals to open up conservation land to mining.
Green Party co-leader Russel Norman said an independent representative of the workers should be on the commission team.
"For the sake of everyone involved, and to ensure that we get to the bottom of the cause of the explosion, the inquiry needs to have maximum credibility and legitimacy," he said.
"To do that it needs to include a representative of workers alongside industry expertise."
The party also urged that the families could speak to the inquiry to offer their views and that the inquiry deal with the causes of the tragedy first to give the families closure before moving onto broader issues.