"This area is not National Park, nor Conservation Park nor does it have any particular reserve status. It is general stewardship land, which is the lowest legal status of protection of land managed by the Department of Conservation."
The area does have conservation values, although there has been some disturbance from previous mining including roads, bulldozer tracks and an artificial reservoir, Dr Smith said.
"The loss of conservation values is compensated by a $22 million package by Bathurst Resources. This will fund pest and predator control over 25,000 hectares of the Heaphy River catchment in the Kahurangi National Park, 4500 hectares on and around the Denniston Plateau, as well as for historic projects on the Plateau itself.
"This is the largest ever compensation package negotiated by DOC for a mine or other commercial venture."
West Coast Environment Network spokeswoman Lynley Hargreaves said new legislation passed in response to public opposition to an proposal to allow mining on schedule four conservation land which meant Bathurst's application would have been subject to public submissions comes into effect on Friday.
Ms Hargreaves said Dr Smith had made "a rushed decision made simply to avoid public consultation".
"Open cast mining on high-value conservation land is not something the public of New Zealand support, and the Government knows that."
She pointed out that her organisation, along with the Royal Forest and Bird Protection Society, was party to ongoing appeals to the Environment and High Courts challenging resource consents issued to the company.
The group is also awaiting a decision from the Supreme Court on declarations sought last year by Bathurst and state-owned Solid Energy, claiming that climate change considerations can't be taken into account in issuing coal mining consents.
In his statement this afternoon Dr Smith said he wanted to signal that "I do not consider it is acceptable to open-cast mine all of the Denniston Plateau".
"The plateau does have unique biodiversity and landscape values from its raised elevation, high rainfall and unusual land form. I wish to see some of the high value areas reserved and put into permanent protection."
Forest & Bird field officer Debs Martin said she was stunned by the decision, "because Denniston Plateau is on conservation land, which means it can only be used for conservation".
"Forest & Bird is devastated that Conservation Minister Nick Smith has today opened the door for an Australian company to mine ecologically significant conservation land on Denniston Plateau."
"Forest & Bird believes the decision is about politics, not conservation. The law prevents the Conservation Minister from taking economic considerations into account when considering access arrangements.
"Everyone - the Environment Court, DOC, external ecologists - agrees that whole ecosystems will be lost if the mine goes ahead. The Minister of Conservation is effectively signing the death warrants of native animals."
Labour's conservation spokeswoman Ruth Dyson said the Government had missed an opportunity to allow conservation groups and Bathurst to reach a compromise over the Denniston Plateau by riding roughshod over the process.
"There was a real possibility of a win-win for both sides that would have seen mining go ahead while other areas were protected for conservation purposes. A compromise could have been reached but the Government has stepped in at the last minute and blown that out of the water," she said.
