Four environmental groups filed a lawsuit against the European Commission on Tuesday in a bid to force the authority to remove natural gas projects from its list of environmentally sustainable activities.

The Commission provoked the ire of climate campaigners and environmentalist pressure groups late last year when it proposed classing some nuclear and gas projects as sustainable under its “taxonomy”, a list meant to define sustainable investing.

The plaintiffs in the new lawsuit, including ClientEarth, the WWF European Policy Office, Transport & Environment and BUND – Friends of the Earth Germany, argue that the sustainable designation for gas runs foul of the European Union’s own taxonomy rules and is at odds with the European Climate Law, which calls for the bloc to achieve net zero greenhouse gas emissions by 2050.