The European Commission on Wednesday defied protests from green campaigners and dissent in its own ranks to give a sustainable finance label to investments in both gas and nuclear power.
Austria immediately responded by warning that it would go to court to try to halt the measure, underlining the passions roused by the issue.
Opponents of gas want to discourage investment in a fossil fuel technology they say only fuels the climate change crisis, while critics of nuclear energy point to the threat posed by accidents and nuclear waste.
Austrian Environment Minister Leonore Gewessler said: "The decision is wrong because it endangers the future... We are giving our children a backpack full of problems... It's irresponsible."
But the EU executive, under pressure from nuclear-powered France and gas-reliant Germany, argues that both have a role to play as cleaner power sources during the transition to a net-zero carbon future.
"The end is a low-carbon future powered by renewable energy. We do not have the capacity for that yet, but we still need to act urgently with all the means at our disposal," EU commissioner Mairead McGuinness said.
"We need to move as fast as we can from the...