National would overturn a ban on new thermal power stations so more gas-generated power could be produced to ensure the country did not suffer blackouts.

Labour said the party's announcement showed a lack of commitment to combat climate change.

Leader John Key today released National's energy policy 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 this winter showed gas electricity stations were essential.

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

Deputy Prime Minister Michael Cullen said National's policy was "vague and backward looking".

"While the rest of the developed world is turning its back on fossil fuels, John Key's party would gamble your children's future on gas and coal, despite New Zealand's abundance of renewable energy," Dr Cullen said.

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."

He said Mr Key was asking the public to trust new coal stations would not be part of the mix.

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

Mr Key said National supported the Government's goal of 90 percent of renewable energy by 2025 and reform of the Resource Management Act would assist that.

"However, we will not let the 90 percent target get in the way of security of supply."

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".

In a speech launching the policy Mr Key also said National's 20 year infrastructure plan would include a new category of state highway called "roads of national significance".

This would include roads such as State Highway 1 that were the backbone of the road network and which would get priority treatment.