The Sizewell C plant is expected to cost £20bn and could provide the UK with 7% of its electricity.
Image source, Sizewell CPrime Minister Boris Johnson has backed plans to part-fund the Sizewell C nuclear power plant on the Suffolk coast, Whitehall sources said.
The government is expected to confirm it will invest in the estimated £20bn project within weeks.
It gave the go-ahead for the new plant in July with negotiations on raising funds for the development continuing.
Other sources have said a final decision will be made in 2023 and will be for the new prime minister to make.
The project, mainly funded by the French energy company EDF, is expected to generate about 7% of the UK’s electricity needs and operate for 60 years.
It would be built next to the existing Sizewell B, which is still generating electricity, and Sizewell A, which has been decommissioned.
EDF has said the new two-reactor plant could generate 3.2 gigawatts (GW) of electricity, enough for about six million homes.
Image source, Andrew Woodger/BBC
A government confirmation of its investment decision would allow private capital to be raised to help fund the development.
But sources have said a final decision will be made by the new prime minister.
Image source, Sizewell C
A letter leaked to the Sunday Times shows the chief secretary to the Treasury – Simon Clarke – has raised concerns that a decision now, could tie the hands of the next prime minister.
According to the paper, Mr Clarke says the costs of Sizewell C are “sufficient to materially affect spending and fiscal choices for an incoming government, especially in the context of wider pressures on the public finances”.
The BBC has approached Mr Clarke for comment but a government source suggested he was fulfilling his duty as chief secretary.
A government spokeswoman said: “Nuclear power has a key role to play as we work to reduce our reliance on fossil fuels and exposure to volatile global gas prices.
“Negotiations are still ongoing on Sizewell C and as these are active and commercially sensitive discussions we cannot comment further.”
Local anti-nuclear campaigners have objected to the plant on several grounds, including that it would have a negative effect on wildlife and campaign group Stop Sizewell C has said it will continue to oppose the project.
Image source, Jenny Kirk/BBC
A spokeswoman said: “Our next prime minister should call Sizewell C in.
“There are so many better ways to spend billions of pounds of taxpayers’ money than on a project that won’t light a single lightbulb for at least a decade.”
Find BBC News: East of England on Facebook, Instagram and Twitter. If you have a story suggestion email eastofenglandnews@bbc.co.uk