Spanish nuclear industry lobby group Foro Nuclear has confirmed it has filed a legal challenge with the country’s top court against a 30% increase of the nuclear waste levy, while the main operators of the plants are moving to join the fight.

The lobby group, whose members include the energy companies operating Spain’s reactors and firms active in the industry, filed the legal action to the Supreme Court in late September, it confirmed to NucNet.

Energy companies Iberdrola and Endesa, the main operators of the country’s nuclear fleet, are moving to file their own appeals, people familiar with the matter had earlier told Reuters.

The new tax, representing an increase of almost 30%, goes to the federal fund for the management of radioactive waste, a task overseen by state nuclear waste agency Enresa.