Campaign group Together Against Sizewell C argued that the UK failed to consider the environmental impacts of the need for a water supply when approving the plant, which is being built by French energy giant EDF.

The group’s legal challenge was rejected by the High Court in June and an appeal against that decision was rejected by the Court of Appeal today.

The building of the plant in southeast England, capable of producing around 3.2 gigawatts of electricity or enough to power around six million homes, was approved in July 2022.

EDF anticipates both reactors at Sizewell C will be operational by mid-2034, its lawyers said at the initial High Court hearing in March.

In September, the UK opened the search for private investment in project, inviting potential investors to register their interest.

The government announced last year that it would support Sizewell C with around £700 million while taking a 50% stake during its development phase.

At the time, then business minister Grant Shapps said the plant would secure “greater energy independence”, a key focus since Russia’s invasion of Ukraine sent energy costs surging.