Forest and Bird says the Government has been looking at opening up 7000 hectares of high-value conservation land to mining.
It says cabinet has considered the plan as it finalises a discussion document on a stocktake of the mineral wealth in protected areas.
The stocktake covers land within Schedule Four of the Crown Minerals Act, which bans mining from areas such as national parks and wildlife sanctuaries.
Forest and Bird's advocacy manager Kevin Hackwell says cabinet is considering removing that protection on high-value conservation land on Great Barrier Island, the Coromandel Peninsula and Eastern Paparoa National Park on the West Coast.
But Mr Hackwell says the Government is worried about the public's reaction and is winding back its proposal.
The Prime Minister and Tourism Minister John Key won't comment on what cabinet is considering.
But he says decisions will be based on what strikes a balance between lifting economic performance and caring for the environment.
Mr Key says from the paperwork he's seen so far he's confident that the balance is in the right place.