The architect of the Treaty settlements process, Sir Douglas Graham, says resolving the Tuhoe claim will be among the most difficult attempted.

Negotiations have been teetering on the edge of disaster after Prime Minister John Key said ownership of Te Urewera National Park was off the table.

Ownership of 212,673ha is a bottom line for the tribe.

Sir Douglas was at the helm of negotiations in the 1990s when first Tainui and then Ngai Tahu signed deeds of settlement.

He said Tuhoe were now "victims" of those settlements because his Government had said national parks were out of bounds during negotiations. That set the precedent, and if broken could see the possibility of deeds being relitigated.

"You can't wreck the country [financially] because one group has said this is their bottom line."

He said he admired both major players in this settlement, but it was possibly the most difficult ever dealt with.

"I would say [Treaty Negotiations Minister] Christopher Finlayson is a reasonable bloke and so is [Tuhoe chief negotiator] Tamati Kruger. They should go away together. Maybe wander up and down the beach, go to the Bahamas. Maybe Lake Waikaremoana.

"Yes. I have no idea how they're going to solve this one."

Asked whether the return of a national park in the Northern Territory this month by an Australian state could be a precedent for these negotiations, Sir Douglas said that should not happen.

"What they do doesn't matter. We've got our own path and we've got to stick to it."

Mr Kruger said Crown officials and tribal leaders had been planning a trip to Australian national parks to see how indigenous ownership worked.

"Like our clean green image, our record on indigenous issues - that we're so far ahead of Australia - it looks a little tarnished."

He said Tuhoe did not accept that other tribes would automatically take the Government back to court, but the Government was talking as if that was a given.