Austria said on Monday it planned to sue the European Commission for allowing Hungary to expand its Paks atomic plant, saying it did not view nuclear energy as the way to combat climate change or as being in the common European interest.
Austria, which shares a border with Hungary, prides itself on supporting clean energy and does not have any nuclear plants of its own.
"We in the government have agreed that there are sufficient reasons to sue (the Commission)," a spokesman for Austrian Sustainability Minister Elisabeth Koestinger said.
"EU assistance is only permissible when it is built on common interest. For us, nuclear energy is neither a sustainable form of energy supply, nor is it an answer to climate change."
EU state aid regulators approved last March Hungary's plan to build two new reactors at its Paks nuclear site with the help of Russia's Rosatom, saying Hungarian authorities had agreed to several measures to ensure fair competition.
The two new blocs will double the plant's nominal capacity of 2,000 megawatts. Hungary aims to start construction on the reactors this year, with the first facility expected set for completion in 2025.
The deadline for filing a suit to challenge the executive EU Commission's decision at the European Court of Justice is Feb. 25, the spokesman said.
In a majority of such complex cases, the European Court of Justice in Luxembourg has found in favour of the Commission.
Austria launched a similar legal action against the European Commission in 2015 over its backing of British plans for a 16 billion pound ($22.24 billion) development of the Hinkley Point nuclear power plant.