Allowing the development of the Rosebank oil and gas field damages the UK’s reputation internationally, Conservative Lord Zac Goldsmith has said, as he hinted at voting for an opposition party come the next election.

The North Sea Transition Authority’s decision to grant consent to Equinor and Ithaca Energy to begin developing the largest untapped reserve of oil in UK waters has ignited fury among climate-minded politicians such as Lord Goldsmith, who accused the Government of losing sight of its climate commitments.

Speaking to BBC Radio 4’s PM programme, the Tory peer said: “It just trashes the UK’s reputation as a reliable, grown up member of the global community, it’s done us immeasurable harm.”

He also attacked the delay to net zero policies such as a ban on new petrol and diesel cars announced last week by the Prime Minister, saying the Conservative Party seems to be in “disarray” and that he may not be able to vote for it.

“If this is the direction that the party is determined to take, and it seems to be, there’s no way I can vote for a party that positions itself, that the Conservative Party is currently positioning itself, on climate and nature,” he said.

“The party that loses sight of the overall goal is not one that deserves to be given the privilege of power.”

The Government said issuing new oil and gas licences and allowing those approved to be developed, such as Rosebank, would boost the UK’s energy security, though when asked, the Department of Energy Security and Net Zero was unable to provide a definition of what energy security means.

Ministers also argue that it would mean less oil is imported from hostile countries such as Russia.

As Rosebank will take until 2026-2027 to begin producing, it will be unable to offer immediate relief to consumer bills and because most of the fuel is likely to be exported, it would at best have only a marginal impact on bills in the future, the Climate Change Committee has said.

Labour’s policy if it wins the next election is to put a stop to new oil and gas licences, though it would honour any that are in place at the time the party gains power.

Speaking to Nick Robinson’s Political Thinking podcast, Sir Keir Starmer said this is a “deliberate” policy to ensure stability in the economy.

“What we’ve said is no new licences to be granted when we’re in power, but we won’t revoke anything, any licences that are granted before we come into power,” he said.

“I’m mindful of the fact that if there’s one thing that has killed growth in the last 13 years, and it has been killed, it’s the chopping and changing lack of strategic thinking.

“And, therefore, as a matter of principle, we will accept, as it were, the baseline that we inherit from the Government if we win that election.”

Environmental Secretary Therese Coffey insisted the new oilfield was part of a transition as the UK “gradually” divests from fossil fuels.

Ms Coffey told C4 News: “We’re still on a journey of transition and it’s important that we still have sources of oil as we make our way to net zero.”

She also defended a reported multimillion-pound taxbreak being handed to the company behind Rosebank.

“It’s important that we continue to attract investment as part of getting towards net zero, that will be done in a variety of ways, one of those is about supporting some of these energy companies in that regard,” she said.