Horizon Nuclear Power has announced it will be ceasing its activities to develop two projects in the UK following a decision by Japanese giant Hitachi to pull out of the scheme.

The decision not to go ahead with building new power stations at Wylfa Newydd on Anglesey and at Oldbury on Severn, in South Gloucestershire, deals a huge blow to the nuclear industry and hopes of creating thousands of new jobs.

Hitachi announced it will end business operations on the nuclear power plant construction project at Wylfa, which was suspended in January 2019.

A statement said: “Hitachi made this decision given that 20 months have passed since the suspension, and the investment environment has become increasingly severe due to the impact of Covid-19.”

Horizon said in a statement: “Horizon will now take steps for the orderly closing down of all its current development activities, but will keep the lines of communication open with Government and other key stakeholders regarding future options at both our sites.”

Chief executive Duncan Hawthorne said: “I understand this announcement will be disappointing for our many supporters who had hoped to see our project through to completion and I would personally like to thank you for your support throughout our time on this project.

“In particular I would like to thank our lead host community of Anglesey in Wales, represented by the Isle of Anglesey County Council and Welsh Government, and the key representatives around Oldbury.

“I would also like to express my sincere gratitude to the many international, UK and Welsh stakeholders who have supported us in the development of our projects.

“Nuclear power has a critical role to play in helping tackle our energy needs, meeting our climate change targets and levelling up the economy through green growth and job creation.

“Wylfa Newydd on Anglesey and Oldbury on Severn are highly desirable sites for new nuclear build. We will do our utmost to facilitate the prospects for development which will bring the major local, national and environmental benefits that nuclear can uniquely deliver as we push to transition to a net zero carbon economy by 2050.”

Tom Greatrex, chief executive of the Nuclear Industry Association, said: “Today’s announcement is disappointing news which nevertheless underscores the urgent need for progress on new nuclear projects in the UK if net zero carbon emissions is to become a reality.

“It is welcome news that Hitachi and Horizon will co-ordinate with the UK Government and other relevant organisations over the handling of sites and possible future options.

“Wylfa is probably the best site in the UK for new nuclear capacity, and has strong community and stakeholder support.

“It is imperative that a way forward is found for the site, to deliver thousands of jobs, hundreds of apprenticeships and millions of pounds of investment into an economic boost for the area while delivering secure, reliable and low-carbon power to underpin the UK’s transition to net zero.”

Alan Whitehead, shadow minister for energy and a green new deal, said: “The cancellation of what would have been the largest energy project in Wales, if it cannot be reversed, could have huge consequences including the loss of between £15 billion and £20 billion in investment. It will also prevent the creation of thousands of jobs in the energy sector and wider UK supply chain.

“We are already in the middle of an economic and unemployment crisis, yet the Government has been completely silent on the potential loss of this power station and the economic impact for Anglesey and the region.

“Ministers must urgently outline whether they plan to seek new developers to take on the Wylfa project, what conversations they have had with Hitachi about the site, and how they will ensure the people of Wales do not pay the price for Hitachi’s withdrawal.”

Horizon was actively developing Wylfa Newydd until January 2019 and planned to have capacity to power around 10 million homes, with Oldbury following on from the North Wales project.

A Government spokesman said: “We recognise that this will be very disappointing news for the people of North Wales.

“Nuclear power will play a key role in the UK’s future energy mix as we transition to a low-carbon economy, including through our investments in small and advanced modular reactors.

“That’s why we previously offered a significant package of potential support to this project that went well beyond what any government has been willing to consider in the past.

“This included taking a one-third equity stake, providing all of the required debt financing to complete construction, and providing generous financial support through our Contract for Difference scheme.

“We remain willing to discuss new nuclear projects with any viable companies and investors wishing to develop sites in the UK, including in North Wales.”

Unite called on the Government to unveil its energy White Paper urgently to allay fears about the future of the UK’s nuclear industry.

National officer Peter McIntosh said: “We desperately need clarity in the energy White Paper which ensures nuclear power is a crucial part of the energy mix in the decades ahead, providing a source of clean and reliable electricity, as well as creating skilled ‘green’ employment.

“A strong commitment to new nuclear will give a confidence boost to the future development of such sites Bradwell (Essex), Moorside (Cumbria) and Sizewell (Suffolk), following the devastating announcement yesterday that Hitachi won’t be proceeding with the Wylfa project.”

The Welsh Government’s minister for economy and North Wales Ken Skates said: “The news from Hitachi today is deeply disappointing.

“There has been a tremendous effort by Horizon Nuclear Power, Ynys Mon Council, the North Wales region and all our partners to bring this important project forward. Now is the time to continue with this strong partnership and build upon those efforts.

“We must not lose sight that Wylfa remains one the best sites in the UK for new nuclear development.

“We will work with our partners to explore all other options, including internationally with key allies, to deliver a sustainable future for the site.”

Anglesey Council leader Llinos Medi said: “This decision is a devastating blow to the Anglesey economy. The Wylfa Newydd project had the potential to transform the Anglesey and North Wales economy, particularly that of North Anglesey.

“I will now be calling for an urgent meeting with both UK and Welsh governments to discuss the future of the Wylfa Newydd site.”