This is established in a judgment in the EU Court on Thursday. It is stated that the EU Commission should first have checked if the Hungarian support was compatible with the EU's procurement rules before giving the go-ahead to Hungary.
The verdict comes after an appeal from the nuclear-critical neighboring country Austria and is welcomed by the environmental organization Greenpeace.
"Hungary can now invest in renewable energy and energy savings that reduce emissions and people's bills immediately", it says in a press release from the organization.
The construction of the new reactors in the Paks 2 power plant in Hungary has been severely delayed and is not expected to start until November at the earliest.
