The Energy Minister's defending the impact the ban on new offshore oil and gas permits will have on the economy

Officials from the Ministry of Business, Innovation and Employment are estimating the ban will cost almost eight billion dollars between 2027 and 2050.

But Energy Minister Megan Woods says the research is trying to quantify the unquantifiable.

She says they aren't denying there'll be a loss of revenue, but they're already helping the regions that'll be impacted.

Woods says the report doesn't take into the account the other work they're doing for the long term management transition.