Two North Island iwi are standing together in opposition to a seabed mining exploration near a marine mammal sanctuary off the Taranaki coast.
Te Kotahitanga o Te Atiawa Trust and Te Kāhui o Taranaki Trust oppose the seabed exploration permit granted to Ironsands Offshore Limited.
Both iwi organisations were told last month about New Zealand Petroleums and Minerals decision to grant the permit.
Te Kāhui o Taranaki Trust chairperson Leanne Horo said both iwi were focused on protecting and enhancing their environment.
"The Ngā Motu/Sugar Loaf Island Marine Protected Area and Tapuae Marine Reserve sit within the Te Atiawa tribal rohe and our Taranaki Iwi tribal rohe," she said.
"So it's concerning to us that the permit has been granted in close proximity to these areas."
The exploration permit falls two nautical miles within a sanctuary that is home to the critically endangered maui dolphin and the rare southern right whale.
Te Kotahitanga o Te Atiawa Trust chairperson Liana Poutu said she was concerned the permit area included a marine mammal sanctuary, which is administered and managed by the Department of Conservation.
"We find it difficult to understand how one arm of government, New Zealand Petroleum and Minerals, can cut across another arm of government and make these kinds of decisions without engagement on the issue."
Ms Poutu said, although it was only exploration at this stage, the implication was if exploration is successful there was an expectation a mining permit would be granted in an area that excluded this activity.
"Fundamentally, the iwi and hapū of Te Atiawa are opposed to this activity," she said.