The UK Government's plans for a nuclear-power renaissance were in disarray after two of the "big six" energy giants pulled out of a venture to build new reactors.

The decision by RWE npower and E.ON not to go ahead with developing nuclear power plants at Wylfa in North Wales and Oldbury-on-Severn, Gloucestershire, threatened the creation of thousands of jobs and undermined UK energy policy, it was warned.

The two German-owned companies said they were looking for a new owner for their venture Horizon Nuclear Power in the light of financial constraints.

The venture was hit by the global economic crisis and Germany's decision to phase out nuclear power.