First Minister Humza Yousaf has been urged to “get off the fence” and oppose plans for the Rosebank oil field in the North Sea to show he is serious about tackling the climate crisis.

An open letter from Friends of the Earth Scotland has urged Mr Yousaf to put pressure on the UK Government to halt plans for Rosebank, which is 80 miles off the coast of Shetland.

Mr Yousaf has previously said he is “not convinced” the development should go ahead but has stopped short of categorically opposing it.

The campaign group said it received backing from hundreds of performers and visitors during the Edinburgh Festival Fringe in August, and its letter has been signed by Frankie Boyle, performer Julia Masli and actor Tam Dean Burn.

In the letter, Mr Yousaf is told: “Until now you have avoided taking a strong position on the future of the oil and gas industry in Scotland, or on the development of the controversial Rosebank oil field.

Read more: Humza Yousaf under fire for lack of climate crisis action and delays

“But the time for sitting on the fence is long past, and your silence on new fossil fuels is becoming a tacit approval for these projects.”

Plans for Rosebank, which contains up to 350 million barrels of oil and is currently one of the largest untapped discoveries in UK waters, is devolved to Westminster, but activists have said Mr Yousaf’s “strong opposition” could put pressure on UK ministers.

Rosebank could produce 69,000 barrels of oil per day – about 8% of the UK’s projected daily output between 2026 and 2030 – and could also produce 44 million cubic feet of gas every day, according to Equinor, the Norwegian firm behind the project.

Boyle’s involvement follows his calls for Prime Minister Rishi Sunak to throw out the Rosebank plans in February.

Read more: Revealed: Rishi Sunak's 'false' claim North Sea oil and gas cleaner than imports

Friends of the Earth campaigner Freya Aitchison said: “People come to Edinburgh from all over the world to perform at and attend the Fringe, and from the outside it looks like Scotland is a green and forward-thinking place.

“From hundreds of conversations in the streets last month, it’s clear that people are frustrated that in reality the Scottish Government doesn’t always live up to this reputation.

“The Scottish Government needs to get off the fence and oppose the climate disaster that is the Rosebank oil field. For too long, they have been dodging the issue and it is time the First Minister gave a clear answer to those asking whether he thinks the development should go ahead.”

Mr Yousaf’s predecessor Nicola Sturgeon previously voiced her strong opposition to Rosebank, and also spoke out against the Cambo oil field in 2021.

Read more: Lorna Slater told to be 'ambitious' with delayed biodiversity strategy

A Scottish Government spokesman said: “The First Minister has been clear that he starts from a position of needing to be convinced that any new oil and gas field should go ahead. Scotland’s future does not lie in unlimited oil and gas extraction.

“Decisions on oil and gas exploration and licensing remain reserved to the UK Government.

“We have consistently called for the UK Government’s climate compatibility checkpoint to be strengthened.

“Without transparent and robust climate compatibility tests, we lack a transparent evidence base to form the basis of decision-making, but we do not believe that Scotland’s future is in indefinite or unlimited extraction of oil and gas.

“The Scottish Government has set out a clear pathway to deliver on global commitments and capitalise on the enormous opportunities offered by becoming a net zero economy – unlocking our potential as a renewables powerhouse.

“Our focus must be on meeting our energy security needs, reducing emissions and delivering affordable energy supplies whilst ensuring a just transition for our oil and gas workforce as North Sea resources decline.”