A Ngati Pukenga kaumatua says the Department of Conservation has not adequately consulted iwi over an upcoming 1080 drop.
DoC will drop the toxin over 4500 hectares of Moehau, a mountain on the Coromandel Peninsula, between June and August.
It has used 1080 in the area before to eradicate pests such as possums and stoats, but this will be its first aerial drop over the mountain.
The chairman of Te Moana a Toi Leaders Forum, Awanui Black, says research shows 1080 poisons the ecosystem and pollutes waterways.
Mr Black says his Coromandel whanau opposes the drop, but DoC does not seem to be listening.
The Department of Conservation says the forest and wildlife on Moehau is incredibly special, and the drop is necessary to protect it from rats and possums.
It says it has consulted more than nine tangata whenua including Ngati Whanaunga, the Moehau Ngati Hei, and the Hauraki Collective.