There are hopes experts will be able to re-enter the Pike River mine drift by the end of the year, but Pike River Minister Andrew Little says it could take longer than expected to get to where any bodies might be.
Little told a parliamentary committee today that the Pike River Recovery Agency was expected to exist until March 2019 but it was now likely to go for longer.
"It looks like the earliest we might start to gain re-entry will be the end of this year, but there's a 2.4km drift to recover and it's likely that will take longer than March next year to do that."
He said it was likely the agency would need more funds than the $22 million already allocated to the recovery.
He is expecting an initial plan for re-entry by the end of this month.
Little said there was a good chance human remains would be found in the drift because two men had made it out.
"With 29 other men down there you have to say there is a reasonable probability that at least some, even if a small number, would have got close to or enough up the drift even if they expired before they got much further, and that's the expectation that we're planning around."
He acknowledged that most would be in the mine workings, and there were no plans to go that far in to the mine.
"We're not planning on re-entering the mine workings, that would be a whole other exercise. The commitment we've made to the families is to recover the drift only."
Little said the men's families were comfortable with that, and were realistic that no attempts would be made to go further in to recover other bodies.
"One of the benefits of involving the families in the decision-making in every step of the way is they get to see the magnitude of the task ahead and the technical demands of the project.
"I think there's also an acceptance that re-entering the mine working themselves, which is a way more complicated layout and therefore project to be undertaken, has a level of technical difficulty that is way beyond what the agency is planning for."
Cabinet established the Pike River Recovery Agency to investigate what happened in the 2010 disaster and look into the possibility of manned re-entry into the mine's drift.
The former National government had rejected the families' pleas for a manned re-entry as too risky.
Agency chief executive Dave Gawn told the committee the mine was still producing methane but measures would be taken to make it safe before anyone went in with nitrogen and fresh air.
"And then essentially just walk in, to put it simply."
Little said he understood Deputy Prime Minister Winston Peter's offer to go in to the drift first still stood.
Peters told a rally of some Pike River families in 2016 that he was confident it was safe to re-enter the mine and made a pledge to go in first.
In April Little entered the mine's portal with Families Reference Group representatives including Anna Osborne and Sonya Rockhouse, who lost family in the disaster that killed 29 men.
Last November he handed over the key to the gate of the Pike River mine access road to the families of the men as a symbol of the Government's effort to re-enter the mine.