"Sooner rather than later we will have to start importing gas and that will be high-priced gas. Consumers will have to pay that price," said Jeffries.
Importing liquid gas for more than 280,000 industrial, commercial and residential customers would also do environmental harm as it needed to be processed as well as shipped here.
The Government said the decision marked the start of a 30-year transition away from fossil fuels in pursuit of a net zero emissions economy by 2050.
The ban on new offshore oil and gas permits is effective immediately, but will not affect existing permits or onshore exploration in the Taranaki region over the next three years. The Government has promised a "just transition" rather than a shock to the oil and gas workforce.
"Transitions have to start somewhere. And unless we make decisions today that will essentially take place in 30 years time, we risk abrupt shocks," said Prime Minister Jacinda Ardern.
Jeffries said NZOG would work its existing permits hard but future growth would be overseas.
"New Zealand Oil & Gas intends to manage the risks associated with the Government's policy change by investing in exploration and production assets in other jurisdictions."
Business NZ chief executive Kirk Hope said the Government's decision to continue to recognise existing permits was important, as doing otherwise would have had a potentially devastating effect on investment into New Zealand.
"It will be important to see what government commitment is being made to affected businesses, and how quickly other high value businesses can be developed to fill the void."
Exporters such as Fonterra, NZ Steel, Methanex and Refining NZ might find their products less competitive in world markets.
"For the longer term, this decision may raise doubts among investors as to the viability of investing in New Zealand business. If a multibillion-dollar energy industry can be banned, what other industries might face the same fate?
"Confidence among both overseas and domestic investors may be the longer term casualty of today's decision," said Hope.
NZOG's Jeffries said this country had previously had a good reputation for regulatory certainty by this was now at risk.
"If you are a big operator and you've got the choice of all the world to drill your wells. We can have the best technical story known to man but if they have that uncertainty around the rules then they will obviously go somewhere else."
His company had a 50 per cent stake in a Barque gas prospect block off the Canterbury coast where exploration work can still go ahead under the Government's new policy.
However, he said it would be more difficult to persuade operators and financiers to back a $50 million exploration well in the prospect, potentially a large source of gas for the South Island.
Natural gas had about half the emissions of coal used by industry in the South Island and was an important backup to renewable electricity generation in the event of low hydro lake levels or little wind for wind turbines.
The Business NZ Energy Council said the exploration ban was a "crude and unnecessary" move that blighted the entire energy sector.
Executive director John Carnegie said there would be no overall reduction in global emissions and potentially an increase in emissions as a result of this ban as global exploration from places with lower environmental standards fills the gap left by our reduced output.
"We strongly support climate change action, but ultimately the cost and efficiency of new energy solutions and therefore the pace of the transition will be dictated by global, not domestic action. Acting sooner will add costs," Carnegie said.
Lobby groups and NZOG were also upset at the lack of consultation.
Jeffries said the industry knew a big call was coming.
"We were all prepared for a moratorium or a delay or a hold while there was dialogue and a debate. The thing that has surprised us is rather than that was the 'no that's it forever'."
