Crown minister Chris Tremain has been accused of double standards for lobbying to ban oil and gas exploration in parts of his back yard.

Tremain, the Minister of Internal Affairs, of Local Government and Associate Minister of Tourism, is a member of a government caucus that supports offering large blocks of New Zealand countryside for oil and gas exploration, including the use of the controversial fracking technique.

But in a message to constituents in his Napier electorate, Tremain has written that exploration has been outlawed from geology around aquifers - or underground wet rock - in Hawke's Bay.

The water sources are crucial for the region's horticulture and agriculture industries.

In an article outlining the "huge" financial opportunity oil and gas exploration offered "The Bay", Tremain wrote: "Sure, there are risks involved, but there are risks in everything we do from driving the car to playing a game of rugby.

"In the case of the oil and gas industry, Craig Foss [National Party MP for Tukituki] and I have worked with the Minister of Energy to remove our Hawke's Bay aquifers from exploration."

In a statement released to the Sunday Star-Times on Friday, Tremain said he stood by the advertorial he had placed in a Hawke's Bay newspaper.

"The East Coast Oil and Gas Study will be released shortly and that will clearly address the economic opportunity for the region and any environmental impacts," he said.

"I would note fracking has also been recently addressed by the independent Parliamentary Commissioner for the Environment. As I said in my article, in my opinion the biggest risk of all is sitting on our hands and doing nothing.

"That is a recipe for low growth, unemployment, and static wages."

He would not address why he made submissions to a fellow minister to "remove" exploration in parts of the Hawke's Bay.

Green Party energy spokesman Gareth Hughes said it was pleasing to see Tremain sticking up for his local region but disappointing he was happy to see exploration - including fracking - being carried out in other parts of New Zealand.

"The question is, if it is so safe why remove it [from Hawke's Bay aquifers]," Hughes said.

"We don't want to have a double-standard where things are based on how ministers lobby other ministers."

Tremain wrote in the newspaper that energy exploration and the Ruataniwha dam project were "two huge opportunities to grow our economy, increase jobs, and lift wages".

The advertorial said the oil and gas industry could be a major financial boom for New Zealand, referring to "a challenging few years" that have included the Christchurch earthquakes, "Pyke River" [sic] and the global financial crisis.

Hughes said it was poor that Tremain had allowed the advertorial to be printed with an incorrect spelling of the Pike River Mine - where 29 men died following an explosion on November 19, 2010.

Tremain had no comment.