Highly sensitive areas have been proposed for coal mining, Forest & Bird chief executive Kevin Hague says.

A secret coal mining plan will carve up "unique and outstanding landscapes", Forest & Bird says.

The affected areas included crucially important biodiversity hotspots in the South Island's Buller Plateau, near Westport, the organisation said on Monday.

The plans were developed for multiple ministers to identify areas for coal mining and areas for protection, Forest & Bird chief executive Kevin Hague said.

FAIRFAX NZ An open cast mine on Denniston Plateau.

"The problem is, they're planning to take the highest value conservation land for coal mining."

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An area known as Whareatea West, on the Denniston Plateau, was proposed for open cast coal mining, he said.

"This is public conservation land, and the most ecologically valuable area on the plateau – without Whareatea West the integrity of the whole plateau is lost."

The "spectacular" Deep Creek area was proposed for protection from open cast mining, but not necessarily from underground mining.

The plans were developed for the Ministers of Conservation, Energy and Resources, and Economic Development, he said.

Economic Development Minister Simon Bridges said it was an "ongoing matter that ministers continue to discuss".

"It is a difficult issue as Buller Plateau has significant economic value but we also understand the need to balance that with the conservation issues."

Buller Mayor Garry Howard said discussions had been ongoing and they had been "anxious to get some agreement for a number of years".

The plans would set conditions which would allow companies to evaluate if they wanted to go ahead with mining projects or not, as they could work out how much environmental conditions would cost up front.

There was a place for coal mining but it was better to have in places where it was subject to environmental conditions, Howard said.

"I would sooner be environmentally responsible and have it mined under conditions, than say 'not in my backyard' and have it mined overseas somewhere where it's not under conditions."

Howard said while mining created economic benefits, the Buller District Council was "very keen to pursue further diversification from any single industry".

"A lot of people talk about tourism as being the saviour for the West Coast. It's very good to be part of the mix, but it's not the saviour."

Coal mining has long been a staple industry on the West Coast, although the amount of mining has fluctuated with the price of coal.

Up to five years ago, the Stockton Mine north of Westport employed about 1000 people, which has since dropped to about 250 following several lay-offs.

In October last year, Phoenix Coal, a joint venture between Bathurst Resources and Talley's Group, purchased the Stockton Mine when it was sold following Solid Energy's collapse.

Bathurst is also working on the Buller Project, which aims to eventually export just under 1 million tonnes of coal each year from several sites in the region, including the Escarpment Project and Cascade mine on the Denniston Plateau.