The Pike River Recovery Agency may look overseas to get the expertise it needs for a safe, manned re-entry into the mine's drift.

And a re-entry won't go ahead unless the plan complies with the Health and Safety at Work Act, and the level of risk is "acceptable" and signed off by the contractor, agency boss Dave Gawn, and finally Pike River Recovery Minister Andrew Little, following independent advice from former Air NZ boss Rob Fyfe.

Contracting an overseas provider is one of the options canvassed in a December briefing paper from the Ministry of Business, Innovation and Employment, released this week by the Pike River Recovery Agency.

As the re-entry plan starts being developed, the agency will begin looking for suitable companies for carrying out the plan.

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"This step is important as the number of companies with the capability to undertake the re-entry work in New Zealand is very limited, and this step will allow the agency to canvass overseas providers also," the briefing paper notes.

It adds that the agency is susceptible to perceptions of bias and a pre-determination to re-enter the mine's drift, and the proposed process includes a number of steps to ensure integrity.

It will create a Technical Experts Group that includes the Pike River families' expert advisers, and seeks input from specialists in geo-technical engineering, coal mine ventilation, underground coal fire, and risk assessment and emergency preparedness.

The agency will also work with WorkSafe and Mines Rescue Trust and, to further avoid outcome-bias, engage with independent third party experts to review the re-entry plan.

It is "vital" that the expert advice to the agency is "impartial and is outcome-focused rather than outcome-biased", the briefing says.

"In other words, it must avoid pre-determination of the decision of whether it is safe to re-enter the drift."

A re-entry plan will not recommend to the minister unless the level of risk is "acceptable" and the plan complies with the Health and Safety at Work Act, following consultation with the Pike River families.​

"It is important to note that not all risk must be eliminated for a decision to be able to be made that re-entry can be done safely," the paper says.

The paper's timeline shows that a decision from the minister on the final re-entry plan is expected in September this year.

The briefing paper notes that MBIE took up some, but not all, of the ideas of Pike River families' expert and former chief mines inspector Tony Forster, but suggested taking up more of his ideas would open the agency up to a perception of bias.

"We are satisfied that the ... re-entry plan has addressed all of the feedback presented by Tony Forster to the extent feasible, whilst ensuring the process will incorporate independent checks and avoid any outcome bias and predetermination," the briefing says.​

Andrew Little was asked for feedback on the briefing, but he simply hand-wrote on it: "No feedback. Approach looks good."

Pike River Families had three expert reports for a manned re-entry that it supplied to previous Government, but in a previous briefing, MBIE said the reports did not fully take into account cost or risk.

But Little has said that he has had more updated information since then, leading him to believe that the prospects for a manned re-entry have improved.

"The indications are that it is technically feasible and increasingly physically feasible," he said late last year.

Solid Energy's position was that manned re-entry was technically feasible, but the risks could not be adequately mitigated.

Obstacles included the crippled integrity of existing roof and wall supports, a lack of full information about the mine's structure, and the risk of rockfall from strata failure, such as a roof collapse.