Britain's nuclear expansion plans have been boosted after Japan's Hitachi signed a £700m deal that will enable the UK to start building the next generation of power plants.
The engineering giant is buying Horizon Nuclear Power, which has the rights to build reactors at Wylfa on Anglesey, North Wales, and Oldbury in Gloucestershire, from its German owners E.ON and RWE npower.
In what it described as the start of a 100-year commitment to the UK, Hitachi confirmed that it intends to progress Horizon's plans to build between two and three new nuclear plants at each site.
The facilities could be feeding electricity into the national grid in the first half of the 2020s and are expected to generate power equivalent to up to 14 million homes over 60 years.
Up to 6,000 jobs are expected to be created during construction at each site, with a further 1,000 permanent jobs at both locations once operational.
Hitachi has also signed supply chain deals with UK engineering firms Rolls-Royce and Babcock International and has pledged to establish a module assembly facility in the UK.
The Horizon venture, which currently employs around 90 people, was set up in 2009 as part of the drive to meet the UK's carbon reduction goals.
But RWE and E.ON put the business up for sale in March after Germany's move to abandon nuclear power in the wake of Japan's Fukushima disaster.
Since then, doubts have grown about the private sector's commitment to the UK's nuclear programme.
Hitachi plans to employ its advanced boiling water technology, which is already in use in four reactors in Japan having been built to time and budget.
Energy and Climate Change Secretary Ed Davey told Sky News the investment was "a huge shot in the arm for the UK economy and a vote of confidence in UK energy policy".
The Cabinet minister dismissed any concerns over safety, insisting that Britain had the "toughest safety regulatory regime in the world".
He added that the technology Hitachi was proposing had "a very good track record" and it was different from the reactors used at Fukushima.
Prime Minister David Cameron said Hitachi's involvement represented a "decades-long, multibillion-pound vote of confidence in the UK".
Mike Clancy, general secretary-designate of the Prospect union, said: "The Horizon venture is an important milestone in securing future low-carbon energy generation capacity within the UK and its importance to local and national economies cannot be overstated."
Gary Smith, national officer of the GMB union, added: "This is positive news. However, we should be under no illusions that there are still real concerns with UK energy policy."
Shadow energy secretary Caroline Flint said Hitachi's decision to buy Horizon was "welcome news" for the nuclear industry, and underscored how important it was that the Government's reforms of the electricity market provided certainty and confidence for other investors.
Tatsuro Ishizuka, vice president of Hitachi, told a news conference in London that the company would invest billions of pounds in UK nuclear operations, stressing that it has already built nuclear power plants safely, on time and on budget.
He said: "Our aim is to build safe nuclear power stations, on time and on budget, to provide long-term, affordable energy."