The Scottish Government may have to delay its new climate change plan as ministers wrestle with “significant concerns” over the strategy caused by Rishi Sunak’s policy U-turn.

On Wednesday, the Prime Minister announced he is delaying several key 2030 targets for decarbonising transport and heat in buildings to 2035 or watering them down altogether.

The PM said he was still committed to the UK’s 2050 net zero pledge, but his strategy means that more drastic action will be needed in the coming decades to keep aims on track.

Scotland’s Net Zero Secretary, Mairi McAllan, labelled the Prime Minister’s announcement as “an unforgivable betrayal”, adding that the UK Government was on the “wrong side of history”.

Read more: Analysis: What message does Rishi Sunak's watered-down net zero strategy send?

She insisted that Scotland’s 2045 net zero pledge remains intact, but suggested that her Government’s new draft climate change plan, due to be published by the end of the year, may have to be delayed.

Ms McAllan told MSP that the shift from Mr Sunak “will have an effect on when I can lay that draft plan”.

She said: “Despite the UK Government reneging on their key net zero commitments, the Scottish Government will remain firmly committed to tackling the twin crises of climate change and biodiversity loss.

“The delivery of Scotland’s climate ambitions is contingent on action by the UK Government in reserved and shared areas.”

She warned that the PM’s intervention “will undoubtedly have serious implications for the delivery of climate ambition here in Scotland”.

Ms McAllan told Holyrood that ministers and government officials are “having to urgently assess the impact on Scotland” of the U-turn by the Prime Minister.

Read more: Sunak warned by advisers off-track net zero aims 'even harder to hit'

Mr Sunak’s plans include weakening the requirement for installing renewable heating systems and home insultation in England, as well as pushing a 2030 ban on new petrol and diesel cars from 2030 to 2035.

The Scottish Government does not have the power to ban the sale of new petrol and diesel cars – with the policy reserved to Westminster.

Nicola Sturgeon pledged to “phase out the need” for new petrol and diesel vehicles by 2030, with Scottish Government officials suggesting the strategy was a mixture of incentivisation and infrastructure improvements.

The Scottish Government ambition was essentially about making electric vehicles the natural choice for consumers by 2030, but this has been thrown into doubt by Rishi Sunak pushing the ban from 2030 to 2035.

The First Minister’s spokesman acknowledged that the Internal Market Act could rule out divergence between the Scottish and UK governments on certain policies, such as new cars and a ban on fossil fuel gas boilers.

Read more: Douglas Ross accuses SNP of halting oil investment amid net zero clash

The spokesman said the Scottish Government was still “to consider the implications” of the PM’s announcement, but said that the Internal Market Act implications “would certainly be something we have to consider”.

He added: “It’s a question of practicality and pace.

“Our position hasn’t changed and frankly, the planet still needs these changes to happen and we just need to get on with it.”

Earlier, Deputy First Minister Shona Robison said that the UK Government “appears determined to undermine the means to deliver the necessary change”.

The Herald: Shona RobisonShona Robison (Image: PA)

She said: “Yesterday’s decision by the Prime Minister to renege on the UK’s key net zero commitments was an unforgivable betrayal of current and future generations. The Conservatives are trading the future of our planet for a cheap electoral ploy.

“The Prime Minister’s announcements that are disintegrating in the face of blistering criticism, not just from industry and business but from some of his own party’s members.”

The Deputy First Minister warned that “the key and most serious and concerning point is that those announcements will have a serious impact and implication for the climate ambitions of not just the UK but Scotland”. She added: “That is unforgivable.”

Ms Robison said: “It is all about the general election and the Tories trying to appeal to their core vote, which is, essentially, about culture wars, being anti-migrants and, now, being anti-environment.

Read more: SNP pledges 'urgent action' after admitting breaching climate laws

“What an unappealing, negative, backward-looking, small-minded prospectus that is, and it will be roundly rejected by the Scottish people once again.”

Mr Sunak has defended his plans, insisting he is “absolutely not slowing down” efforts to combat climate change.

Pressed on the prospect of legal challenges over his plans, he said he had “absolute confidence and belief” the UK will hit its targets, having “consistently over-delivered in all our previous carbon budgets”.

He said: “We are absolutely not slowing down efforts to combat climate change. I am very proud of our country’s leadership.”