Maori in Northland's Kaipara District are planning protest action to stop a tidal power project in their harbour.
Crest Energy has consent and some funding from the Government to install large turbines in the sea at the entrance to the Kaipara harbour.
Tangata whenua say the Government has been so keen to find alternative energy sources, it has backed technology that is untested and poses a threat to marine life.
A spokesperson for Te Uri o Hau, Mikaera Miru, says the hapu will now begin organising a protest flotilla to confront Crest when it starts work in the harbour.
He says a hui-a-iwi will also be called in the next week to discuss making part of the harbour a wahi tapu and imposing a ban on Crest's planned activities.
