Simon Bridges says National would have no problem approving coal mining on conservation land that isn't "pristine".
The Government on Saturday said it had declined an application to build an open-cast mine across 12 hectares in the Mt Rochfort Conservation Area on the South Island's West Coast.
Mr Bridges told The AM Show on Monday he wasn't sure if the party agreed or disagreed with the Government's decision, because it's yet to be discussed in caucus.
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But he said National "definitely" opposes what he's calling a "blanket ban" on mining in conservation areas.
"A third of New Zealand is conservation estate. Some of it's pristine - there shouldn't be coal mining. But some of it's scrubland."
Nearly 30 percent of New Zealand is conservation land, but not all of it is Schedule 4 land - the most protected. The previous National Government did plan to allow mining in Schedule 4 land, but backtracked after 50,000 people took to the streets in Auckland in 2010.
A few years later Mr Bridges, then Energy and Resources Minister, signed off a block offer for exploration in Victoria Forest Park - the biggest of its kind in New Zealand. He later admitted he had never heard of it before he signed it off.
Victoria Forest Park isn't Schedule 4 land, and nor is the Mt Rochfort Conservation Area, east of Westport. Nonetheless, Conservation Minister Eugenie Sage called it "an undisturbed area which is precious and unique and supports complex and diverse habitats for threatened plants and wildlife", including kiwi, snails and lizards.
Energy and Resources Minister Megan Woods said the "irreversible and permanent costs to the natural environment" outweighed any economic benefits a mine would bring.
Mr Bridges said he would allow mining to go ahead on "low-level" conservation land.
"We've always had that policy, and here's why - actually, it's jobs. If you don't do this where there aren't big conservation values at stake, you're just importing the coal from overseas. That may make people feel virtuous, but I don't know if it actually [makes New Zealand greener]."
He specifically ruled out allowing mines on Schedule 4 land.
The Government earlier this year said it would no longer be issuing exploration permits for fossil fuels, with a few exceptions. National has promised to reverse that ban.