Sir Keir said Britain’s energy security had been “held hostage” by Russian President Vladimir Putin for “too long”, which has resulted in prices “skyrocketing at his whims”.

“I’m putting an end to it – changing the rules to back the builders of this nation, and saying no to the blockers who have strangled our chances of cheaper energy, growth and jobs for far too long,” he said.

The process of choosing to loosen rules on where nuclear reactors could be built began under Rishi Sunak’s Conservative government with a consultation in January 2024.

Ministers said Britain is considered one of the world’s most expensive countries in which to build nuclear power, and a new Nuclear Regulatory Taskforce will be established to speed up the approval of new reactor designs and stream line how developers engage with regulators.

Conservative shadow energy secretary Andrew Bowie said it was “about time” Labour followed his party’s lead in recognising the benefits “of stable, reliable, baseload nuclear power”.

But Doug Parr, policy director of Greenpeace UK, claimed the government had not applied “so much as a pinch of critical scrutiny or asking for a sprinkling of evidence”.

“The Labour government has swallowed [the] nuclear industry spin whole,” he said, adding: “They present as fact things which are merely optimistic conjecture on small nuclear reactor cost, speed of delivery and safety.”

While the overall cost of nuclear power is comparable with other forms of energy, nuclear plants are extremely expensive to build.

The head of the Nuclear Industry Association, Tom Greatrex, called the reforms the “strongest signal yet” towards growth and clean power.

Gary Smith, GMB’s general secretary, said the union has repeatedly said “there can be no net zero without new nuclear”.

Referring to Sizewell C, the site on the Suffolk coast on which then prime minister Boris Johnson pledged a new nuclear reactor on in 2022, he added: “[It] stands ready and waiting for the green light to power up our country’s future.”

The government has not yet made a final decision on Sizewell C, which is not due to come until the spending review later this year. The final choice on the design of the SMRs will also come at the same time.

Two new nuclear reactors are also being built at Hinkley Point C in Somerset, which are due to open in 2030.