The Government and Ngai Tahu are in dispute over compensation for the impact that the emissions trading scheme will have on its forestry assets.
Climate Change Minister Nick Smith says the iwi claims the Crown breached its good faith agreement with Ngai Tahu in its settlement on forestry land.
The Crown had a duty to disclose the impact any deforestation policy would have.
Dr Smith says although officials knew there would be an impact, it was a mistake that Ngai Tahu was not told rather than a conspiracy.
He says Ngai Tahu estimates the loss caused by the devalued land is $120 million but the Crown's estimate is $40 million.
Dr Smith is ruling out financial compensation.
