As part of efforts to meet climate targets and boost energy security, Britain is seeking to build new nuclear plants to replace its ageing fleet.
Yet Sizewell C has struggled to attract additional investment and the government has already committed around 2.5 billion pounds of taxpayers' money to the project.
The Development Expenditure Scheme proposed on Friday would help to fund the project's development up to and including the point when a financial investment decision can be taken on whether to fund it through to completion - or when there are enough other investors on board to continue.
“We are committed to Sizewell C, which will play an important role in helping the UK achieve energy security and net zero, while securing thousands of good, skilled jobs and supporting our energy independence beyond 2030," a spokesperson for Britain's Department for Energy Security and Net Zero (DESNZ) said in an emailed statement.
The spokesperson said government expects to make a final decision on the project by the end of the year.
Julia Pyke and Nigel Cann, joint managing directors at Sizewell C, said in a separate statement: "This latest commitment enhances our ability to deliver key works over the next year, from developing local infrastructure to progressing significant earthworks onsite, new offices, and training facilities".
If built, Sizewell C would be expected to generate enough electricity to power around 6 million homes.
It would be only the second new nuclear plant built in Britain in more than two decades, after EDF's Hinkley Point C which has had several delays and cost overruns and is currently expected to start operations in 2029, with an estimated cost of between 31 and 34 billion pounds at 2015 prices.
When initially proposing the project, EDF said Sizewell C would be around 20% cheaper than Hinkley C.
DESNZ said "funding for the Devex Scheme will be provided subject to relevant approvals".
