Inquiry important, but not today - PM

John Key met rescue teams and family members of the missing miners yesterday. Photo / Mark Mitchell

Prime Minister John Key is indicating that a commission of inquiry will look into the cause of the explosion in the Pike River mine.

Mr Key visited the site yesterday - the second time since Friday's explosion - meeting the rescue teams and some of the family members of the 29 men still stuck in the mine.

He said the rescue team agreed with the decision not to enter the mine until it was safe to do so.

"I specifically went around and asked the individual members of the rescue team to make sure that they were unified in their view that they shouldn't be going into the mine at this time, and they are totally unified.

"They await a time when it is safe - they want to get their mates out, but this is not the time to do that."

He would not be drawn on whether he thought the miners were still alive.

"Any talk of anything other than a rescue mission in my view would be speculative."

Mr Key defended the safety record of mining in New Zealand and rejected a suggestion that safety standards were below those in Australia.

"I have no reason to believe that New Zealand safety standards are any less than Australia's and in fact our safety record for the most part has been very good."

A review of mining inspectors carried out under the previous Labour Government found the two appointed by the state were appropriate, he said.

A commission of inquiry was likely to be set up as opposed to a royal commission, Mr Key said.

"I don't want to speculate on what the make-up of a commission would look like.

"There are going to be many questions asked about how such an event could occur and what it means for the future. Those questions are for another day."

The company had told him there had been no warning of the explosion.

"They monitor airflow going into the mine and coming out for methane levels. There are methane alarms in the mine and miners carry their own methane-gauging devices. And none of those, to the best of the company's knowledge, indicated any problems.

"It is a highly, highly irregular event and we'll need to understand what the cause of that is."

Energy Minister Gerry Brownlee will remain in Greymouth while Mr Key may return later in the week.