European Commission (EC) president José Manuel Barroso has told European countries that they “cannot avoid the question of nuclear energy”.

Barroso’s comments came at an energy conference in Madrid on 1 October, which included various energy industry leaders.

But his pro-nuclear remarks and those of two other commissioners have caused controversy.

During the energy conference, Barroso argued that the EU must hold a “full and frank” debate on the nuclear issue as part of wider considerations to reduce CO2 output.

Competition commissioner Nelly Kroes and energy commissioner Andris Piebalgs seconded Barroso’s comments. Kroes said she is “completely in favour of nuclear power”, while Piebalgs said member states must “have the courage” to debate the issue.

Piebalgs told Spanish newspaper El Pais that up to 30% of the EU’s energy should be produced from nuclear to address energy security concerns.

But the European Parliament’s Green and European Free Alliance condemned the nuclear endorsement by Kroes and called on Barroso to withdraw Kroes’ competency for the nuclear sector.

The group stated: “Impartiality is fundamental to the legitimate exercise of duties by the EU competition commissioner. By clearly stating a preference for nuclear power, Kroes has cast serious doubt over her ability to be impartial in decisions on competition matters relating to nuclear energy.”

Meanwhile, in a statement following a separate conference in Vienna on the issue of nuclear energy as a response to climate change, Germany’s Ministry for the Environment said the “inherent safety, environmental and proliferation risks” of nuclear energy make the technology “incompatible” with the concept of sustainable development.

Nuclear “does not provide a viable option to combat climate change”, according to the statement.