Tuhoe leaders say a Crown apology for 19th century injustices would be meaningless unless tribes who fought with colonial forces also say sorry.

The Herald understands Treaty settlement negotiations have explored what shape a formal Crown apology might take, but sources say if an apology is owed then Ngati Porou, Ngati Kahungunu and Te Arawa should also show some contrition.

Those three iwi were instrumental in the 1870 and 1871 pursuit of Te Kooti, whom Tuhoe allowed to take refuge in Te Urewera after massacres in Poverty Bay.

Historian Paul Moon said it was important to remember that only sections of hapu or individuals from each tribe would have been involved in the fighting.

Similarly, not all of Tuhoe supported or were complicit in sheltering Te Kooti.

But the suffering Tuhoe were subjected to was different from that of other iwi who faced war and land confiscations.

"The Crown had almost a sort of scorched earth policy. Villages were burned and crops were destroyed, but there was almost an ethnic cleansing in a way.

"I think the intensity of what they've suffered is seen now in their desire to get a full apology. It's not just the standard Crown apology which they'll photocopy and change the name of the iwi. They want something far more substantial."

It was an interesting situation as the Crown could not compel other iwi to apologise.

"It's very humiliating if someone apologises for your behaviour and you don't consent to it - there's some real problems there," Dr Moon said.

Te Arawa representative Toby Curtis would say only that the iwi-to-iwi matter was extremely sensitive.

"First and foremost this matter would have to be discussed by Te Arawa."

Others spoken to had an aversion to dredging up past deeds of ancestors.

AUT University pro vice-chancellor Maori Pare Keiha has Rongowhakaata tribal links to Te Kooti and had ancestors who were killed by the religious and guerrilla leader.

But he was wary of the concept of an apology.

"I have no doubt whatsoever that our own people were not all kind and caring - but that's also the history of humankind.

"I'm always very cautious to revise history because whether you call it civil wars or internecine fighting, none of us were there.

"With hindsight, history often has a habit of distorting the truth. If we carry around [that] hurt, none of us would get out of bed in the morning."