France, Poland and five other countries have written to the European Commission, warning that EU climate change policies could hamper nuclear power's role in cutting CO2 emissions.
The letter, dated March 19, arrived as Brussels is finishing landmark green finance legislation designed to steer cash into low-carbon projects, with the Commission yet to decide whether the EU rules will label nuclear power as a sustainable investment.
In the letter to the Commission, seen by Reuters, the countries said the EU should do more to put nuclear power on a level footing with other low-carbon technologies in climate policies, including the sustainable finance rules.
"We are highly concerned that the Member State's right to choose between different energy sources and the right to determine the general structure of the energy supply is currently heavily limited by EU policy making, which excludes nuclear power from more and more policies," they said.
It was signed by French President Emmanuel Macron and the Prime Ministers of Hungary, Poland, Czech Republic, Romania, Slovakia and Slovenia.
EU leaders in December agreed to cut their net greenhouse gas emissions at least 55% of 1990 levels by 2030 - a goal the Commission says will require extra energy sector investments of 350 billion euros a year this decade.
While nuclear technologies are eligible for EU research funding, the countries said a focus on technologies that will take decades to become commercially viable risked sidelining near-term projects.
EU countries are divided over nuclear, which produces roughly a quarter of EU electricity from the 13 states that use it. Supporters promote its low CO2 emissions, while opponents raise concerns over hazardous waste, and the delays and spiralling costs of recent projects.
France generates around 70% of its electricity from nuclear. The other countries behind the letter use the fuel - which comprises roughly 56% of power produced in Slovakia, 48% in Hungary and 35% in Czech Republic - except for Poland, which wants to build reactors to reduce its dependency on coal.
The Commission said it could not confirm receipt of the letter.
"We have a neutral position on that as the European Commission," EU climate policy head Frans Timmermans said of nuclear power at an online event hosted by the University of Pittsburgh this month.
EU states should compare nuclear's costs and benefits to those of renewable sources when considering new reactors, Timmermans said.