The proposed Sizewell C nuclear power plant on the Suffolk coast is reportedly under review as the government looks to limit spending.

The new reactor, located about 20 miles south of the Norfolk border, was expected to be built by French energy firm EDF.

Boris Johnson promised £700million 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 now told the BBC: “We are reviewing every major project – including Sizewell C.”

The total cost of the project could be around £20billion.

Sizewell C is not expected to begin generating electricity until the 2030s; the similar reactor at Hinkley Point C in Somerset began construction in 2016 and will not be online until 2027, although this is partly due to the impact of the Covid pandemic.

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 a roughly £60bn financial black-hole following former Chancellor Kwasi Kwarteng's mini-budget announcement in September.