Solid Energy is withdrawing its nitrogen machine - a key tool in the Pike River re-entry hopes - from the mine site and sending it out of the country.

The move was revealed today by West Coast-Tasman MP Damien O'Connor. Solid Energy confirmed it, but said it was unrelated to the board decision on the re-entry plans, which was due to be delivered to the families at a meeting in Greymouth tomorrow morning.

Mine families' spokesman Bernie Monk said it was "not looking bright" for tomorrow.

One of the last parts of the re-entry up the drift, or the main entry tunnel, was to pump inert nitrogen into the tunnel area, to displace methane to make it safe. The main tunnel could then be ventilated, and Mines Rescue could have entered.

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Acknowledging the poor timing, Solid Energy spokesman Bryn Somerville said the board decision about whether to proceed with the re-entry, and the withdrawal of the machine were unrelated.

"Solid Energy has been asked by BOC, which owns the plant, if we would release it," Mr Somerville said. "We understand it is needed at another mine in the Pacific region and so have agreed. We also understand that if such a plant is needed in future for the project, BOC would work with us to supply one."

However, Mr O'Connor said the nitrogen machine would have been a key component of any recovery operation.

"(Prime Minister) John Key has to front up and explain why he is allowing a State-owned enterprise to walk away from a recovery operation that international experts say is both possible and safe to carry out."

Mr O'Connor said the families deserved to have any information and evidence from inside the drift that could further explain the causes of the disaster that killed 29 men, almost four years ago.

"John Key always claimed money was not the issue, but I suspect the financial challenges faced by Solid Energy, along with the zero risk approach it is taking, is their excuse for not proceeding. John Key must intervene on behalf of the families," Mr O'Connor said.

Mr Monk said today the nitrogen machine was paid for out of the re-entry fund and was not Solid Energy's to take away.

If the news delivered to them tomorrow was against the re-entry they would be asking Solid Energy, which was struggling with a massive debt, to step aside and "let someone in who can do the job".

Mr Monk said he had dealt with six government ministers on the matter - Kate Wilkinson, Gerry Brownlee, Phil Heatley, Chris Finlayson, Simon Bridges and now Michael Woodhouse, who had "never been in contact".

He had also dealt with seven chief executives and three chairmen.

"It's not fair what they've done to us," Mr Monk said.

Mines Rescue chairman Dave Stewart said this morning they had not heard anything officially but still supported the re-entry.

BOC spokeswoman Melissa Hayes said work had commenced to relocate its nitrogen gas generation plant membrane, which was urgently required at another site.

"As a result, both Solid Energy and BOC are working together to ensure it is moved as safely and as quickly as possible to its new location. While we do need to relocate the current plant membrane, we will work with Solid Energy to supply nitrogen from alternative sources if required," she said.

Prime Minister John Key said he understood Solid Energy planned to talk to the victim's families tomorrow "about their future involvement" and latest findings.

He said the removal of equipment at the mine had nothing to do with the company's announcements tomorrow.

The emergency equipment had been moved to support a mining incident overseas, he said.

Mr Key is also travelling to the West Coast with Environment Minister Nick Smith and Energy Minister Simon Bridges tomorrow to meet those affected by the Pike River disaster.

Asked whether the families should expect bad news, Mr Key said: "I wouldn't characterise it in that way."

He added: "I'd like to talk to the families from the Government's perspective face-to-face and with the dignity of making sure we talk to them first."

Simplified Pike River re-entry proposed

Meanwhile, the mining experts employed by the Pike River Mine families have proposed a simplified re-entry to mine owners Solid Energy, in a 17-page report which offers solutions to many concerns raised.

The report by international coalmining advisers Bob Stevenson and David Creedy, dated October 26, concludes that the re-entry could be achieved safely.

They proposed a re-entry that was less complex, initially on foot and by a highly trained team, in fresh air. It would be halted at the first sign of unsatisfactory ground support.

The report includes a list of all hazards identified, and what could be done to mitigate them.

For example, there could be a risk of roof collapse around the Hawea Fault, which the families' experts accepted was "extremely disturbed", but additional support could be put in, such as a pre-formed concrete tunnel.

To reduce the risk of a vehicle fire, the first re-entry could be on foot.

The report also reveals a report by Pacific MGM found major risks, and 600 things which needed to be "controlled". But the families report said all 600 would not all be in place at any one time.

It also shows someone called Rob Thomas thought the workmen would not have enough experience. The report counters they would be highly experienced Mines Rescue staff.

The Rocksil plug had been tested successfully in Australia.

The report reveals the 3km nitrogen line has already broken; but the only consequence was to delay things.

The families recognised there was only one way in and out of the mine. They asked for a quick resolution to the legal debate over the lack of a second escapeway.

The report also asks the Solid Energy board to "consider the journey they have taken the families down over the past three years and the hope given to them by the September 2013 announcements by Solid Energy environmental manager Mark Pizey and Tony Forster, chief inspector of mines, when without doubt they intimated that a credible-feasible plan had been agreed and the work for re-entry would start".

The advisers are unpaid.