Sir Keir Starmer will allow the Rosebank oil and gas field west of Shetland to go-ahead if the Labour leader gets the keys to Downing Street, according to sources.

He would not block the development which is expected to secure permission from the Conservative government in the next few weeks.

Sir Keir’s likely endorsement of the new North Sea field is the latest revision of his green policy from a seemingly hardline plan to stop all new oil and gas developments.

He is understood to have assured Rosebank licence holder Equinor, the Norwegian state-owned energy company, that he will not stand in its way.

The Labour leader was forced to soften his approach to green transition after criticism from industry and trade union figures concerned over jobs and energy security.

He was also forced to row back on a pledge to commit £28 billion a year to green transition.

Following the backlash, Labour has promised not to revoke any fossil fuel extraction licences granted before the next general election. The Sunday Times says he has relayed his current position to a number of energy giants ahead of launching his party’s 2030 clean power mission in Edinburgh tomorrow.

BP and Shell are among 76 companies bidding for 115 new licences to drill in the North Sea. The outcome of the UK’s 33rd offshore oil and gas licensing round is expected to be announced this autumn.

In an interview with Daily Business earlier this month, Labour’s Shadow Business Secretary Jonathan Reynolds said a Labour government would not revoke current licences to drill in the North Sea but there would be no further development in the region. A ban would be imposed “from day one” of Labour moving into Downing Street, he said.

He rejected claims that the country needs to continue producing oil and gas in order to guarantee its energy security. Both those assertions now seem to have been modified by the party to include pending licences and to acknowledge the role that oil and gas will play for decades to come.

A Labour spokesman said: “The Labour Party has said we will not grant new licences to explore new fields and has also consistently said we will not turn off the taps by shutting down existing fields or revoking existing licences.

“We recognised that oil and gas will play an important role for decades to come and will not allow a cliff-edge in the North Sea.”

Rosebank is one of the largest oil and gas fields in the North Atlantic, capable of producing up to 500 million barrels of oil.

On Monday Sir Keir will unveil his green plans, including his earlier commitment to create a publicly-owned clean energy company, GB Energy.