A big expansion of nuclear power was launched on Wednesday as a German consortium bought two sites for building new reactors and committed itself to a huge investment programme.

RWE and Eon, two German-owned companies that are already large energy suppliers in Britain and have teamed up to build new nuclear plants, bought the sites at Wylfa in Anglesey and Oldbury in Gloucestershire in an auction held by the government’s Nuclear Decommissioning Authority.