A geologist who warned of the dangers of Pike River three years before the tragic explosion says it will be impossible for the new government agency to safely reach the guts of the drift.
Yesterday Cabinet approved the establishment of the Pike River Recovery Agency, including a target of re-entry by March 2019, with the ultimate decision to re-enter resting with Pike River Minister Andrew Little.
The agency would be set up from January and work closely with the Pike River families as it considers if re-entering the mine can be done so safely.
Geologist Murray Cave, who warned of the highly gaseous nature of the mine in 2007, questioned whether the matter had now become too political.
He said the Government's rhetoric implied that the agency wanted to be able to reach the "guts of the mine, which I don't think is really possible at all".
"In the area where the fresh air base was, we know that area has collapsed and there's a lot of rubble there," he told Newstalk ZB.
"Getting through all that rubble will be almost technically impossible, I would have thought, to do safely."
But former chief mining inspector Tony Forster, who has been advising the Pike River families, rejected that.
"It's not insurmountable."
He said the infrastructure at the mine had been downgraded or completely dismantled following not to continue with a re-entry plan at the start of 2014, including the power supply and the monitoring system.
"There's significant work to be done to get us back to the starting line. I believe the mine can be made safe for people to go back down. It's a complex operation. There will be a degree of uncertainty."
The agency will have a budget of about $7.6 million a year for three years.
Families' spokesman Bernie Monk said the new government agency was a huge step forward.
"This is really important to us, but it is also important to all of New Zealand. We should not be a country where a crime-scene goes unexamined for seven years."
Amy Adams, National's spokeswoman for Pike River, said Labour had wound back its initial promise to the families of a re-entry and was now close to that of National's - that safety was paramount.
"The Government is now recognising that it cannot waive health and safety laws, rush or force a re-entry."
She said National had supported a re-entry provided it could be safely achieved. "I would encourage the Government to listen to the experts."