Entrepreneur and philanthropist Gareth Morgan has taken a swipe at the Green Party and some conservationists.
He says that the majority of New Zealanders see them as "lefties", "extremists" or "nutters," which in the long run is holding back their cause of protecting the environment.
"We still have a Green Party that refuses to go into coalition with National. What the hell is that about? Is this a party concerned with conservation? Or is it a far-left group using conservation as a Trojan horse for another agenda?"
At Forest and Bird's conference, Face up to the Future, Morgan also took aim at some conservationist groups he calls the "green extreme" or "loony left".
In particular, he says that their opposition to mining and fracking is not evidence-based, and fails to consider employment and the economy.
"If you're pro-conservation the problem here is you're increasingly being regarded as anti-economic growth. That is not a constructive position to take. It needlessly alienates huge numbers of people," Morgan said.
The philanthropist has written about climate change and is driving a million dollar project to eradicate pests on the Antipodes sub-Antarctic islands.
He says conservationists need to have the courage to "disown" activist groups.
Nic Vallance, spokesperson for Forest and Bird said: "That's actually really a pet peeve of mine. The majority of New Zealanders do react quite passionately about the environment, but when people like Gareth paint them into a corner and say 'don't worry about them, they're just tree huggers, they're just greenies', it makes them really uncomfortable."
The Green Party says it considered a coalition deal with National, but the parties are incompatible on many environmental issues.
"We've seen National's agenda to sell off assets, to have a drill it, mine it, irrigate it resource extraction policy. That goes to the heart of nature. The Green Party is about a sound economy based on a healthy environment," Green Party MP Eugenie Sage said.