Ministers from France, Poland, the Czech Republic and six other EU countries wrote to the European Commission this week urging it to open up EU renewable energy targets to include hydrogen produced from nuclear energy.
EU countries and lawmakers have been preparing for negotiations next week on the law, which will guide the pace of Europe's renewable energy expansion this decade.
Hydrogen can also be produced from electricity, so the EU wants to set sectoral targets for hydrogen made from renewable electricity.
The nine countries' letter, seen by Reuters, said the EU should include nuclear energy - which is low-carbon, but not renewable.
At least nine EU countries oppose the idea, among them Germany, Denmark, Austria and Luxembourg, officials said.