Grave worries as Russian military domineers staff at captured Ukrainian nuclear power plant

Russian commanders are now in control of Europe's largest nuclear power plant, an "extremely concerned" UN watchdog has warned.

Rafael Mariano Grossi, director-general of the International Atomic Energy Agency (IAEA), said staff running the plant were having to report decisions to a Russian military commander, leading to concerns about its safe operation.

"In order to be able to operate the plant safely and securely, management and staff must be allowed to carry out their vital duties in stable conditions without undue external interference or pressure,” he said, adding that he was "extremely concerned" about the situation.

The nuclear power plant in Zaporizhzhia, in the south-east of the country, first came under attack from invading Russian forces last week, leading to a fire in a training building just a few hundred metres from the reactors.

Levels of nuclear radiation at the site have not increased and the reactors were not damaged in the assault. However, an explosion at the facility could lead to a disaster "10 times larger" than the notorious 1986 Chernobyl disaster, Ukraine's foreign minister said on Friday.

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Communications between the plant and Ukraine's nuclear regulator were also down, the IAEA said, with telephone lines and email not working and mobile phones available only intermittently. It also said problems with food supplies had led to low staff morale.

On Sunday Vladimir Putin, Russia’s president, blamed Ukrainian "radicals" for the fire during a two-hour call with Emmanuel Macron, the French president. However, he agreed to talks with the IAEA and Ukraine to ensure safety at nuclear sites in the country.

Russia has also taken control of the area surrounding the defunct Chernobyl reactor. Security experts said it had been taken because of its strategically useful location on the route between the Ukrainian border with Russian ally Belarus and Kyiv, the Ukrainian capital.

Staff there, including guards and engineers, have not been able to stand down from their roles since February 23 - the day before Russia took control, the IAEA said. It called on Russian forces to allow them to rest.

It came as Russian forces fired at a Ukrainian science facility which housed a nuclear installation, according to Ukrainian security services.

Rockets were launched at the Kharkiv Institute of Physics and Technology on Sunday, which houses nuclear fuel elements as part of an experimental program designed to make the energy source safer and more environmentally-friendly, according to its website.

Its scientists were also part of a team which worked on a landmark European nuclear fusion project based in Oxford which last month marked record-breaking results, raising hopes for fusion as a future clean power source.