The cost of building the proposed Sizewell C nuclear plant in Suffolk could be up to £5bn less than that of Hinkley Point C in Somerset, work on which has already started.

French energy giant EDF expects the Hinkley Point scheme ? Britain’s first new nuclear plant since Sizewell B opened in 1995 ? to cost around £20bn.

But according to a report in The Times, EDF believes that it can reduce the cost of Sizewell C by as much as 25% through efficiencies resulting from the use of the same technology and a similar design.

A spokeswoman for EDF Energy, the group’s UK arm, said that the story in The Times was not based on a briefing from the company.

However, she added that EDF had said previously that costs would come down as Hinkley Point C is part of a series of EPRs (third generation pressurised water rectors) being developed around the world.

A reduced construction cost for Sizewell C is widely seen as crucial if the project is to go ahead, with cost of renewable energy now having fallen well below the “strike price” agreed between EDF and the UK government for power generated by Hinkley Point C.