Theresa May has given the go-ahead to the Hinkley nuclear power project but with new security conditions on the £18 billion deal.
Her decision, to be officially announced in the Commons on Thursday, ends weeks of speculation over whether the two-reactor scheme would go ahead.
But critics hit out as it looked likely the price promised to French firm EDF for Hinkley’s electricity has not been lowered under the new terms.
Business Secretary Greg Clark said it is an "important upgrade of our energy supplies" and a "major step forward" for the UK's nuclear power programme that could create 26,000 jobs.
Under terms due to be signed by the previous administration, the Chinese government was to contribute some £6 billion towards building the reactors at Hinkley Point, but it could then in turn have led to a further Chinese-designed power station at Bradwell in Essex.
It has already emerged that security is one issue officials have been reviewing, and that at least one senior member of Ms May’s team has serious reservations about Chinese involvement in British nuclear power.
Asked about security concerns, Mr Clark said: "It was right for the UK Government to look seriously at all the components of the deal and what we have decided is that for critical infrastructure generally, we want to make sure our powers in this country are comparable to those of others to be able to check that national security considerations are taken into account.
"What we've done here in Hinkley is required that EDF, the principle operator, guarantees, makes a commitment, that they won’t dispose of their stake without the government's consent."
He added: "In future, all other nuclear power stations will be subject to the same regime."
The delay in finalising the agreement threatened to overshadow Ms May’s first major international summit, the G20 in China, earlier this month.
China’s ambassador to the UK had warned the delay meant the two countries were at a "crucial historical juncture" and that "mutual trust" could be at risk if it fell.
Nick Timothy, a senior adviser to Ms May, previously warned that China “could use their role to build weaknesses into computer systems which will allow them to shut down Britain’s energy production at will”.
There have also been claims that the price promised to EDF for Hinkley’s electricity at £92.50 per MWh, more than double the current wholesale price, was too expensive.
Labour's shadow energy minister Barry Gardiner said: "I think they should now have been renegotiating with EDF on the strike price to make it lower for the British bill-payer.
"The point is this. Originally, the Government calculated that this would cost bill-payers, not the Government, bill-payers, £6 billion over the lifetime of this project.
"In fact the National Audit Office has come out and said it will not be £6 billion, they have said it will be £30 billion."
Liberal Democrat energy and climate change spokesperson Lynne Featherstone said she was disappointed with the Government's decision to move forward with Hinkley Point.
She went on: "The circumstances have changed. With the cost of renewables rapidly falling, Hinkley is now very bad value for money for the British taxpayer and should be abandoned immediately.”
Green Leader Caroline Lucas said: "Instead of investing in this eye-wateringly expensive white-elephant, the Government should be doing all it can to support offshore wind, energy efficiency and innovative new technologies, such as energy storage."
The new reactors that will be built at Hinkley are also of unproven design, with the two being constructed elsewhere beset by budget overruns and delays.
EDF has had problems with its side of the agreement too - the company’s finance director, Thomas Piquemal, resigned earlier this year, fearing Hinkley could lead to the firm’s insolvency.
Greenpeace executive director John Sauven said: “This decision is unlikely to be the grand finale to this summer’s political soap opera.
"There are still huge outstanding financial, legal and technical obstacles that can’t be brushed under the carpet. There might be months or even years of wrangling over these issues.
"That’s why the Government should start supporting renewable power that can come online quickly for a competitive price."
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