Rishi Sunak appears set to water down some of the Government’s net zero pledges to ensure they are “proportionate”, in a move that has drawn sharp criticism from across the political spectrum and campaigners.

The Prime Minister confirmed he will make a speech this week to “set out an important long-term decision”, following reports that he would use one to row back on green targets.

This could include weakening the plan to phase out gas boilers from 2035 and delaying the ban on the sale of new petrol and diesel cars – currently due in 2030 – by five years, the BBC reported.

We are committed to Net Zero by 2050 and the agreements we have made internationally, but doing so in a better, more proportionate way.

Mr Sunak said on Tuesday that the Government remains committed to the target of net zero emissions by 2050, but will achieve it “in a better, more proportionate way”.

He said that politicians “of all stripes have not been honest about costs and trade offs” and accused previous Tory governments of taking “the easy way out, saying we can have it all”.

Mr Sunak, who is attempting to draw a dividing line with Labour before the next general election, sought to position himself as the bringer of “real change” who would “put the long-term interests of our country before the short-term political needs of the moment”.

The Prime Minister insisted the Government is not “losing our ambition or abandoning our commitments”, but looks set to renege on a host of policies put in place by Conservative governments to hit the net zero goal.

The prospect of a major shift in the Conservatives’ approach to green policy was quickly condemned by senior figures in the party.

Former Cop26 president Sir Alok Sharma warned that “for any party to resile from this (climate action) agenda will not help economically or electorally”.

Tory former Cabinet minister Sir Simon Clarke tweeted that “it is in our environmental, economic, moral and (yes) political interests as @Conservatives to make sure we lead on this issue rather than disown it”.

Some Tory MPs are considering writing letters of no confidence in the Prime Minister if he goes ahead with the changes, the PA news agency understands.

The party’s success in the summer’s Uxbridge and South Ruislip by-election, won largely through a campaign against the expansion of the ultra low emission zone (Ulez), has led to other MPs to call for Mr Sunak to water down or abandon net zero pledges.

The Prime Minister could reportedly also axe plans for new energy-efficiency targets for private rented homes.

In his late-evening statement, he said: “For too many years politicians in governments of all stripes have not been honest about costs and trade offs. Instead they have taken the easy way out, saying we can have it all.

“This realism doesn’t mean losing our ambition or abandoning our commitments. Far from it. I am proud that Britain is leading the world on climate change. We are committed to Net Zero by 2050 and the agreements we have made internationally, but doing so in a better, more proportionate way.

“Our politics must again put the long-term interests of our country before the short-term political needs of the moment.

“No leak will stop me beginning the process of telling the country how and why we need to change.

“As a first step, I’ll be giving a speech this week to set out an important long-term decision we need to make so our country becomes the place I know we all want it to be for our children.”

Conservative MP Dame Andrea Jenkyns backed the plans, telling ITV News: “The country and globally we’ve been through a difficult time with Covid and also the war in Ukraine. We cannot ask people on top of that to change the heating system to change the cars.

“And I don’t want to see the working classes pay for, you know, the middle classes having electric cars.”

His short stint as PM will be remembered as the moment the UK turned its back on the world and on future generations. A moment of shame

But Chris Skidmore, a Conservative former energy minister who has become increasingly outspoken on net zero, told PA: “If this is true, the decision will cost the UK jobs, inward investment, and future economic growth that could have been ours by committing to the industries of the future.

“It will potentially destabilise thousands of jobs and see investment go elsewhere. And ultimately the people who will pay the price for this will be householders whose bills will remain higher as a result of inefficient fossil fuels and being dependent on volatile international fossil fuel prices.

“Rishi Sunak still has time to think again and not make the greatest mistake of his premiership, condemning the UK to missing out on what can be the opportunity of the decade to deliver growth, jobs and future prosperity.”

Tory peer Zac Goldsmith, who quit as environment minister in June with a scathing attack on Mr Sunak’s environmental “apathy”, accused the Prime Minister of “dismantling” the UK’s credibility on climate issues.

He said: “His short stint as PM will be remembered as the moment the UK turned its back on the world and on future generations. A moment of shame.”

Liberal Democrat climate and energy spokesperson Wera Hobhouse said: “What Rishi Sunak should see in front of him is the opportunity to embrace the industries of the future and protect the coming generations from the catastrophic impacts of climate change.

“Instead, he has cowered to the delayers and deniers like the disgraced Liz Truss and adopted wholesale their policies.”

Labour’s shadow energy secretary Ed Miliband said: “This is a complete farce from a Tory government that literally does not know what they are doing day to day.

“Thirteen years of failed energy policy has led to an energy bills crisis, weakened our energy security, lost jobs, and failed on the climate crisis.”

Green Party MP Caroline Lucas said: “This decision would be economically illiterate, historically inaccurate and environmentally bone-headed. This absurd rollback will mean higher energy bills, colder homes, fewer jobs, more air pollution and more climate chaos.”

Hannah Martin, co-director of Green New Deal Rising, said: “Once again this Government has shown that they are hell-bent on breaking their promises and doing nothing to stop climate chaos. Just weeks after the hottest summer on record Rishi Sunak has decided to ignore science and stoke a culture war.

“Whilst global leaders are meeting to discuss how to tackle the climate crisis, he has stayed home to set fire to some of the only remaining climate policies this Government had left.”

Jess Ralston, head of energy at the Energy and Climate Intelligence Unit, said: “As the rest of the world is rushing to invest in net zero industries, any further rowing back by the UK would leave our international standing further tarnished.”

Friends of the Earth’s head of policy, Mike Childs, said: “Rolling back on key climate commitments as the world is being battered by extreme flooding and wildfires would be morally indefensible.”