The New Zealand Business Council for Sustainable Development is backing National's call to overturn a ban on new thermal power stations.

But Greenpeace have joined Labour criticism, saying it is a backward step and the focus should be on sustainable production.

National Party leader John Key released National's energy policy yesterday and said his party in government would overturn the ban on new baseload thermal power stations which he said put the security of electricity supply at risk.

Mr Key said while New Zealand should still develop renewable resources, events this winter showed gas electricity stations were essential.

"Our country simply cannot afford to have insecure supply of electricity," Mr Key said.

The New Zealand Business Council for Sustainable Development chief executive Peter Neilson said the ban was unnecessary.

"We don't think banning new thermal baseload is necessary to encourage investment in renewables. It is happening already. One major generator, with approval to build a combined cycle gas plant, has shelved that in favour of massive investment in geothermal and wind power," he said.

"We say trust the market. A price on carbon will do the job of encouraging renewables."

Deputy Prime Minister Michael Cullen said National's policy was "vague and backward looking" and the public was being asked to trust that new plants wouldn't be coal-fired.

Greenpeace said it was untrue that fossil fuel generation was needed and increased demand could be met by renewables.

Mr Key emphasised National's focus was on gas not coal and its emissions trading scheme (ETS) would mean no new coal stations unless improved technology reduced pollution.

National's ETS would be introduced within nine months of taking office and was likely to result in the phasing out of the use of coal at the Huntly power station, Mr Key said.

Dr Cullen said it was "incomprehensible" that National could release an energy policy without giving details of its ETS.

"Without these details, today's announcement is simply a mandate for heavier reliance on coal and gas -- which is not the way of the future."

Mr Neilson said the ETS needed to pass soon to provide certainty for investors, and to prevent delaying decisions to invest in low-carbon technology.

Dr Cullen accused National of talking up a possible power crisis this winter to justify its decision.

National would reform the Resource Management Act (RMA) to make it easier to get new generation projects going including removing ministerial veto and opportunities for frivolous objections.

The new priority consenting process would mean major national infrastructure consents would be called in and determined centrally with a decision required within nine months.

Mr Key said National would review the multiple agencies running the electricity sector and said one possible outcome of the this was scrapping the Electricity Commission.

National's wider energy policy also included plans to expand oil and gas exploration by spending $25 million over three years on seismic exploration, as well as reviewing the minerals regime to ensure it encouraged the sector.

NZ Petroleum Exploration and Production Association executive officer John Pfahlert said the policy would guarantee an affordable and secure supply of electricity.

He said more seismic surveying would encourage offshore investment in the sector.

Mr Pfahlert said the policy was in line with the New Zealand Energy Strategy's goals which promote affordability and security of supply.

However, Green Party co-leader Jeanette Fitzsimons said the policy relied on "drill and hope" and would see consumers more dependent on international markets where liquefied natural gas was imported.

She accused National of cronyism; "...they want to borrow from future generations so that their fossil fuel friends can make more money today".