A North Island iwi is seeking the return of the Waitangi Treaty Grounds using the UN Declaration of Indigenous Rights but the government says it cannot be used in that way.
Maori Affairs Minister Pita Sharples this week flew to New York without publicly revealing he was to make a speech announcing New Zealand would endorse the declaration.
The previous Labour government had refused to sign, concerned about how it could be used domestically.
Ngapuhi academic David Rankin has written to the UN Social, Humanitarian and Cultural Committee and asked for a process to be set in place for the Treaty Grounds to be returned to his hapu -- Te Matarahurahu.
The request was under article 32 of the declaration, which requires states to obtain free and intelligent consent before doing anything that affects the land of indigenous people.
Mr Rankin said that consent was not given and now the hapu wanted to assert its right to reclaim it under the declaration.
Mr Rankin said it would be a test for the UN and the New Zealand Government.
"If the land is not returned the New Zealand government will be exposed in front of the international community as failing to keep its obligations."
Prime Minister John Key has been clear to state affirmation of the declaration would not change the legal framework in New Zealand as it was a non-binding, aspirational agreement.
Treaty Negotiations Minister Chris Finlayson said the declaration could not be used to support claims for the return of privately or trust-held land such as the Waitangi Treaty Grounds.
"It was predictable, but still disappointing, that some fantasists and bush lawyers would use New Zealand's affirmation of the (declaration) as a basis for these sorts of groundless claims," Mr Finlayson said.
"Affirming the (declaration) does not affect the existing legal framework of New Zealand. The Crown has clear policies on the way the government conducts the settlement of historical grievances in the treaty process.
"These policies work well, and they are not affected by the affirmation of the declaration."