"Existing nuclear plants alone will need 50 billion euros of investment from now until 2030. And new generation ones will need 500 billion!" Thierry Breton told the Journal du Dimanche newspaper.

Breton also argued that an EU plan to label energy from nuclear power and natural gas as "green" sources for investment was a vital step towards attracting that capital.

The EU is consulting its member states on that proposal, with internal disagreement on whether the power sources truly qualify as sustainable options.

France has led the charge for nuclear power -- its main energy supply -- to be included, despite robust opposition from Austria and scepticism from Germany, which is in the process of shutting all its nuclear plants.

The proposal says the EU Commission "considers there is a role for natural gas and nuclear as a means to facilitate the transition towards a predominantly renewable-based future".

Currently the bloc gets 26 percent of its energy from nuclear power, but Breton estimated that by 2050, that would be reduced to around 15 percent.

The proposal also states that for nuclear power, appropriate measures should be put in place for radioactive waste management and disposal.

And it calls for the building of new nuclear power plants to be conditioned on permits given out before 2045, while work to extend the functioning of existing plants would need to be authorised before 2040.