A nuclear power station in Suffolk previously championed by Boris Johnson is at risk of being scrapped as Rishi Sunak races to find ways to cut spending.
The £20bn Sizewell C project has been hailed as a key part of Britain’s efforts to improve its energy security, though critics have baulked at the costs and length of time it will take to complete.
The Government’s spending review means the development could be delayed or even scrapped entirely, a Whitehall source told The Telegraph.
It comes as Rishi Sunak reviews a string of policy pledges made by his predecessors, Mr Johnson and Liz Truss.
The Prime Minister has repeatedly warned that “difficult decisions” will need to be made as the Government tries to put Britain back on a stable economic footing after weeks of turmoil.
Chancellor Jeremy Hunt will deliver the Government’s tax and spending plans in the Autumn Statement on November 17.
“We are reviewing every major project – including Sizewell C,” a government official told the BBC, which first reported the move.
Sizewell C, which would produce enough electricity to power six million homes, was proposed by state-owned French giant EDF.
The Government granted planning permission in July despite warnings from the Planning Inspectorate that it could reduce water supply available for households. Negotiations on funding are still ongoing.
It would be completed in the early 2030s, becoming just the second nuclear plant built in the UK since the opening of Sizewell B in 1995.
Nuclear power plants have become a key part of the Government’s aim to boost energy security, with ministers hoping they will eventually produce 25pc of the country’s power.
They are also seen as an important way of achieving net zero goals.
But Sizewell C had attracted criticism even before the recent economic turmoil due to its huge costs and the delay in getting reactors online.
The fresh overhaul will raise concerns that other major projects could be shelved, including plans for a high speed rail line in the north of England.
Ms Truss had pledged to build the line – nicknamed Northern Powerhouse Rail – which would connect northern towns and cities from Hull to Liverpool via Bradford.
But Business Secretary Grant Shapps has hinted that the plans will be scaled back.
He told the BBC: “There wasn’t really much point in going and blasting new tunnels through the Pennines… It’s not true to say we’re not delivering on what we said we would do on levelling up the north.”
Meanwhile, HS2, another major rail project aimed at linking London with the Midlands and the North, has also been plunged into doubt following policy flip-flops regarding a line connecting Manchester and Leeds via Bradford.
Mark Harper, the new transport secretary, this week said no decision had been made on HS2 amid spending cuts and that the Government was “looking at all of the options”.
A Treasury spokesman said infrastructure projects were still a priority, adding: “HS2 is under way, within budget, and supporting 28,000 jobs, we are also seeking to approve at least one large-scale nuclear project in the next few years and aim to speed up the delivery of around 100…