Ukraine’s state-run atomic energy company said Russian missiles flew at low altitude over Europe’s largest nuclear power plant in southern Ukraine on Tuesday, and reiterated warnings that Russia’s invasion could lead to a “nuclear catastrophe.”

Energoatom issued its latest warning about the risks caused by the war with Russia on the 36th anniversary of the world’s worst nuclear accident at the now defunct Chornobyl plant, in what was then Soviet Ukraine.

The company said cruise missiles had flown over the Zaporizhzhia nuclear power plant during an airstrike which local authorities said hit a commercial building in the city of Zaporizhzhia, killing at least one person.

“Missiles lying at a low altitude directly over the site of the ZNPP [Zaporizhzhia nuclear power plant], where there are seven nuclear facilities with a huge amount of nuclear material, poses huge risks,” Petro Kotin, Energoatom’s acting chief, said.

“After all, missiles could hit one or more nuclear facility, and this threatens a nuclear and radiation catastrophe around the world,” he was quoted as saying in a statement issued by Energoatom on the Telegram messaging app.

Energoatom said Russian troops, who have occupied the plant since March 4, were keeping heavy equipment and ammunition on the site.

“Thirty-six years after the Chornobyl tragedy, Russia exposes the whole world to the danger of a repeat of the nuclear catastrophe!” it said.

Russia did not immediately comment on Energoatom’s statement. It has previously offered safety assurances about Ukraine’s nuclear power facilities since launching what it says is a “special military operation” on February 24.

Russian troops also occupied the decommissioned Chornobyl nuclear power station soon after invading Ukraine but have since left the site.

Rafael Grossi, the head of the International Atomic Energy Agency (IAEA), was due to visit Chornobyl on Tuesday, the anniversary of the explosion and fire there on April 26, 1986.