Brussels is facing the threat of legal action and the potential sidelining of its landmark sustainable finance rules by EU governments that do not want nuclear power or natural gas to be labelled as green investments.

Energy ministers from Austria and Luxembourg told the Financial Times that they would pursue a lawsuit against the European Commission over its so-called green “taxonomy” rules, while a Spanish deputy prime minister said Madrid could opt to use its own green framework, excluding nuclear power and natural gas.

The complaints heap pressure on the European Commission, which has proposed that nuclear technology and some forms of natural gas be designated as sustainable investments under sweeping rules designed to help stamp out greenwashing in the finance industry.