Plans to build a major new nuclear power plant in England are reportedly under review as the government seeks to limit spending.
Sizewell C, about 48 kilometres north-east of Ipswich in Suffolk, was expected to provide up to 7 per cent of the UK's total electricity needs.
Boris Johnson promised £700 million ($784.6m) of taxpayers' money to the project in his final policy speech in early September as he sought to make energy security part of his legacy as prime minister.
But a government official has since told the BBC: "We are reviewing every major project ― including Sizewell C."
The total cost of the Sizewell C project could be about £20 billion, according to reports.
It is not expected to begin generating electricity until the 2030s.
A similar reactor at Hinkley Point C in Somerset began construction in 2016 and will not be online until 2027, although this is partly owing to the impact of the pandemic.
The UK last opened a nuclear plant in 1995, although the Hinkley Point C project is well overdue and Sizewell C was given planning permission in July.
Proponents of the site say it can help get the UK to run on zero-carbon power, but others say the cash would be better spent on wind farms or insulation.
The government is seeking opportunities to reduce spending after the Institute for Fiscal Studies warned last month that the state faces an estimated £60 billion financial black-hole following the mini-budget announcement in September.
The Treasury has since pulled back on a number of previous unfunded tax cuts or spending plans.
Reports suggest the chancellor is also considering a tax increase on the sale of assets such as shares and property to fill a £50bn black hole in the public finances.
An increase could also be imposed in dividend tax, in a move that would come as a blow to entrepreneurs.
A source close to Jeremy Hunt confirmed the tax increases were under consideration, but said no decisions had yet been taken ― emphasising that "we are two weeks away" from the highly anticipated autumn budget.
The chancellor last month announced that the two-year energy price freeze for all households will now run for just six months.
Mr Hunt said at the time that the universal energy price guarantee will finish in April, with the government launching a review on how to then support bills after this period.