Austria and Luxembourg decided to jointly sue the European Commission for allowing Hungary to expand its Paks atomic plant.

Hungary’s plan to build two new reactors at its Paks nuclear site with the help of Russia’s Rosatom had been approved by EU state aid regulators in March. The regulators said that Hungarian authorities had agreed to several measures to ensure fair competition.

The two new reactors 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 due to be completed in 2025.

“We are going to actively support Austria’s claim,” Luxemburg’s environment minister Carole Dieschbourg said.

“It is important that no public funds be invested in nuclear power. It is definitely the wrong way.”

Austria’s new government, an alliance between Chancellor Sebastian Kurz’s conservatives and the far-right Freedom Party, has pledged to continue Vienna’s decades-long policy of opposing nuclear power.

The European Commission has said it will defend its decision in court. In many such complex cases, the European Court of Justice in Luxembourg has found in favour of the Commission.