The Government proposes subsidising the survey work of mining companies in the Mt Aspiring and the Rakiura National Parks, apparently leaked documents suggest.
Green Party co-leader Metiria Turei said she had been "leaked" documents revealing the Government was planning to grant a $4 million subsidy to the mining industry for survey work in the parks.
The geological survey would also include Kahurangi National Park, in the northwest of the South Island, with all three parks deemed protected because of their high conservation values.
It appeared the Government was signalling some of these areas would be removed from schedule four of the Crown Minerals Act, which prohibits mining, she said.
If the surveys proved favourable for the exploration companies, mining companies could be prospecting in the parks in less than 10 years, Mrs Turei said.
Asked in Parliament about the mining subsidy, Prime Minister John Key said "I am not in a position to confirm that at this time".
"I think when the discussion document is released, New Zealanders will have an opportunity to see how balanced the approach that the Government is taking is - that is, the balance between our economic opportunities and our environmental responsibilities," he said.
A spokesman for Energy and Resources Minister Gerry Brownlee said the minister would not comment on the issue as it formed part of a discussion document, which was expected to be made public next week.
However, in a speech at the New Zealand-Australia Investment Forum in Auckland last week, Mr Brownlee said a conservative estimate of the value of New Zealand's onshore minerals, excluding lignite, was about $180 billion - representing a a $40 billion increase on his earlier estimates.
"We are a lucky country. New Zealand is a mineral-rich country with considerable untapped potential," he said.
The export value of the 40sq km of land used for mining in New Zealand was $175,000 per hectare, compared to dairy farming using 20,000sq km, with an export value of $3500 per hectare.
"There is vast potential for more investment in this sector."
Forest and Bird advocacy manager Kevin Hackwell said the latest twist in the debate over mining on conservation land showed "how Mickey Mouse this whole thing is".
Surveying work was not prohibited from schedule four land, so "the industry could pay for this themselves".
"But it does stop mining."
