Plans to build a new nuclear power station in the UK, creating over 20,000 jobs, have collapsed after Toshiba said it was pulling out of the project.

The Japanese engineering giant is to wind up its NuGen business, which was going to build three reactors at Moorside in Cumbria, enough to generate 7% of the UK’s energy needs.

More than 20,000 workers would have been employed to build the £15 billion plant, close to the Sellafield complex, and 1,000 people would have been employed once electricity was generated from 2024.

Unions and the Labour Party attacked the Government for not intervening to ensure the project went ahead, but anti-nuclear campaigners welcomed the decision, saying it proved nuclear power was not economically viable.

Toshiba said in a statement: “After considering the additional costs entailed in continuing to operate NuGen, Toshiba recognises that the economically rational decision is to withdraw from the UK nuclear power plant construction project, and has resolved to take steps to wind up NuGen.”

NuGen said the announcement came after 18 months of negotiations with a range of potential new owners.

The announcement continued: “Unfortunately, it has not been possible to successfully conclude those negotiations.

“NuGen has retained a team to support the implementation of a winding-up process and will work with Toshiba and its other stakeholders.

“Whilst NuGen will not be taking the project forward, the Moorside site in Cumbria remains a site designated by Government for nuclear new build, and it is now for the Nuclear Decommissioning Authority as the owner of the site and the Government to determine its future.”

Justin Bowden, national officer of the GMB union, said: “The British Government has blood on its hands as the final sad but predictable nail is banged into the coffin of Toshiba’s jinxed jaunt into nuclear power.

“Relying in this way on foreign companies for our country’s essential energy needs was always irresponsible.

“In the wreckage that passes for a joined-up UK energy policy, the question now is whether Government has finally learned the mistakes of Moorside?”

A Business Department spokesman said: “We understand that Toshiba have faced a difficult decision in ending their involvement in new nuclear projects outside of Japan in light of their well-known financial challenges.

“All proposed new nuclear projects in the UK are led by private sector developers, and while the Government has engaged regularly with the companies involved, this is entirely a commercial decision for Toshiba.

“Nuclear has an important role to play as part of the UK’s diverse energy mix as we transition to a low-carbon economy, but in each case projects must provide value for money for consumers and taxpayers.

“This Government remains committed to new nuclear through the Industrial Strategy Nuclear Sector Deal as well as consenting the first new nuclear power station in a generation at Hinkley Point C.”

Greenpeace UK executive director John Sauven said: “The end of the Moorside plan represents a failure of the Government’s nuclear gamble.

“Their flawed approach to making our economy low carbon has dashed the hopes of prospective workers and businesses in Cumbria that should have been centred around renewable technologies.

“The Government now needs to rapidly deploy renewable energy to fill the gap.

“That means restarting onshore wind, a new deal for expanding solar power, and upping ambition on more offshore wind.”

Sue Ferns, senior deputy general secretary of Prospect union, said: “This is devastating news for Cumbria and the wider energy sector.

“The nuclear industry and wider supply chain currently employ thousands of people in the North West of England.

“The long-term future of this could be on the line if we can’t move forward with building Moorside.”

Rebecca Long Bailey, shadow business secretary, said: “Today’s announcement by Toshiba is hugely concerning for the future of the sector and the thousands of jobs it would bring to Cumbria.

“Unfortunately, it’s not surprising given the Government’s long indecision and refusal to step in.”

Unite union official Ritchie James said: “Today’s news is a cruel blow to the prospects for the North West economy and the future of thousands of highly-skilled jobs in construction and operations, once it was up and running.”

Sara Medi Jones, acting general secretary of CND, said: “Nuclear energy isn’t just dirty and dangerous, this announcement shows once again it’s not economically viable.

“Nuclear proponents will say the Government should have done more to save the Moorside plant, but this is an industry that already relies on enormous state subsidies at taxpayers’ expense.”