The Bay of Plenty tribe of Ngāi Te Rangi says the Government's approach to overlapping claims is a breach of Māori customary rights.
The allegation follows the initialling of a deed of settlement agreement giving 12 Hauraki tribes rights to Tauranga Harbour which Ngāi Te Rangi wasn't consulted about.
Ngāi Te Rangi kaumātua Hauata Palmer says the three tribes of Tauranga Moana have stated that the management of the harbour sits with them and the Govt.
"We object to Hauraki having any part of this," he said. "The Govt has reached a settlement with Hauraki but hasn't sought any agreement from us."
Mr Palmer claims the agreement falls under the Govt's current approach to overlapping claims which disregards Māori customary rights.
But the Treaty Negotiations Minister says nothing is finalised in so far as the moana is concerned and it will be the subject of ongoing negotiations between all iwi over the next 12 months.
Meanwhile, Ngāi Te Rangi is supporting Ngāti Whātua ki Ōrakei and its High Court action against the Crown that tikanga is part of common law and must be considered by the Govt during settlement negotiations.