A campaign group has begun a legal challenge of the government's decision to grant Sizewell C planning permission on the same day Boris Johnson pledged £700million to the project.

Together Against Sizewell C (TASC) issued judicial review proceedings in the High Court following an unsatisfactory response to their pre-action protocol letter sent to Business Secretary Kwasi Kwarteng at the beginning of August.

Planners had recommended that the project be refused planning permission, but Mr Kwarteng overrode their advice and gave the 3.2-gigawatt power station the greenlight on July 20.

East Anglian Daily Times: Prime Minister Boris Johnson (left) during a visit to EDF's Sizewell B nuclear power station in Suffolk.Prime Minister Boris Johnson (left) during a visit to EDF's Sizewell B nuclear power station in Suffolk. (Image: PA Wire/PA Images)

The legal challenge centres on the fact that a permanent water supply for the project has not yet been put in place, the idea that other means of creating power had not been fully considered, and the length of time that there would be nuclear material on the site.

TASC is being supported in the challenge by Suffolk Coastal Friends of the Earth and Stop Sizewell C.

Pete Wilkinson, TASC chairman, said: "TASC is delighted to have the support of Friends of the Earth Suffolk Coastal and Stop Sizewell C in this vitally important battle for the soul of the Heritage Coast.

"Like so many other individuals and organisations in the area, they have worked tirelessly to demonstrate the flaws in the government's plans for more nuclear development on this fragile coast and their support for TASC's legal challenge demonstrates a determination and unity of purpose among opposition groups which strengthens our collective resolve to see off Sizewell C and EDF's plans to disfigure and ruin this part of Suffolk."

Rowan Smith, from Leigh Day's solicitors, said: "Our client is incredibly concerned that the government has ignored the recommendation of the Examining Authority to give the go-ahead to Sizewell C.

"For such a locally and nationally important issue, it was vital that the Secretary of State properly assesses the environmental impacts of the project.

"However, TASC believes that fundamental legal errors were made, particularly in respect of water, alternatives to nuclear power, local wildlife and climate change. We hope these arguments will now be fully scrutinised by the court."

The Department for Business for Business, Energy and Industrial Strategy declined to comment due to the ongoing legal process.