Forest and Bird claims the Government is secretly planning open cast coal mines for the most significant conservation area in the Denniston Plateau.
The great spotted kiwi, fernbird, West Coast green gecko, and many rare insects and plants would be affected by the plans, according to the conservation group.
It said the unique landscapes of the plateau, in the Buller District, would be carved up and the best areas made available to new mining company Phoenix Coal.
Phoenix is a joint venture between Bathurst Resources and Talley's Group.
The plans were developed for the Ministers of Conservation, Energy and Resources, and Economic Development, according to Forest and Bird chief executive Kevin Hague.