Lord Howell of Guildford, George Osborne’s father-in-law, told the House of Lords that the Chinese were actively discussing a ‘plan B’ if the existing £21 billion plan fails.

Addressing a fellow peer, Lord Howell, the Conservative energy secretary under Margaret Thatcher, said: ‘Is my noble friend aware that the Chinese also have a plan B, which is to bypass EDF altogether and to build two smaller reactors on the Hinkley C site, and to do it rather quicker than the present Hinkley C plans?’

He later told The Times that he had previously had private meetings with Chinese delegations, and said: ‘This is the view of informed think tanks and a deduction of the way they must be thinking.’

His warning will put greater pressure on the Hinkley C project, which is planned to provide about seven per cent of the country’s electricity.
Yesterday, EDF announced a 16 per cent increase on the cost of the project since October, from £18 billion to £21 billion.

The French energy giant also admitted that the project would not be finished before 2027, which is a decade later than was originally proposed.

There have been repeated delays with designing and construction of the plant, which will take at least nine and a half years to build once it has been signed off. This is not now due to happen until September.

Lord Howell suggested that the second plan would involve building two smaller nuclear reactors at Hinkley Point ‘rather quicker’.

Senior intelligence and military figures warned that national security could be threatened by Chinese nuclear reactors after fears that technological ‘trapdoors or backdoors’ might be put into computer systems. This would allow China to bypass Britain’s security measures.

Lisa Nandy, the shadow energy secretary, told The Times: ‘If there is a secret Chinese plan B for Hinkley, ministers should tell us precisely what that is.

‘With uncertainty over both the timetable and the cost of this project, it is now imperative that the government offer reassurance that British jobs will be protected, costs on households will be kept under control and that binding pollution targets will not be put at risk.’

A Department of Energy spokesman said: ‘There is no proposal for the Chinese to build a reactor at Hinkley.’