The families of the men who died in the Pike River mine have written to the Police Commissioner asking him to continue efforts to retrieve their bodies.
Twenty-nine workers died in a series of explosions which began at the West Coast mine near Greymouth on 19 November last year.
The police say it is up to the receivers for Pike River Coal to decide what happens next, but Prime Minister John Key says all options have been exhausted and the mine will be sealed.
A spokesperson for the families, Bernie Monk, whose son died in the disaster, says good progress has been made in making the mine safe for re-entry and he doesn't understand why officials would abandon their efforts at this stage.
Mr Monk says the lawyer acting for the families has asked Police Commissioner Howard Broad to delay ending the recovery operation until they can hire a senior and experienced West Coast mining expert to advise them.
Engineering geologist David Bell, who is helping monitor the mine, says the atmosphere inside is still variable and it remains unsafe to enter.
Professor Bell met mining experts from Australia and the police on Friday to advise what should happen to the mine.
He says various strategies have been discussed but nothing has been agreed or implemented, and discussions will now have to take place between the company and the Police Commissioner.