"Intelligence services have received information that Russia is considering the scenario of a terrorist act at the Zaporizhzhia nuclear plant -- a terrorist act with the release of radiation. They have prepared everything for this," Zelensky said in a statement on social media.

Fears for Europe's biggest nuclear plant, which have persisted throughout Moscow's Ukraine offensive, have been exacerbated by the destruction of a dam that provided the cooling water for the plant.

The Kremlin rejected Zelensky's claims that Russian forces could be orchestrating a radiation leak, pointing to a recent visit to the facility by the head of the UN's nuclear agency.

"This is another lie. There were just contacts with the IAEA at the site -- a very high assessment from the IAEA (International Atomic Energy Agency). They saw everything, everything they wanted to see," Kremlin spokesman Dmitry Peskov told reporters.

Moscow meanwhile on Thursday announced that UN nuclear chief Rafael Grossi would be arriving in the Russian region of Kaliningrad to meet with the head of Russia's nuclear agency.