The safety of Europe's largest nuclear power plant, located in Ukraine's southeastern region of Zaporizhzhia, has been a concern since Russian forces seized it over a year ago during Moscow's war on its neighbor.

It has been subject to frequent shelling that caused several power outages vital to cooling the plant's reactors.

Ahead of Ukraine's expected counteroffensive, fears have increased that a nuclear disaster could occur amid increased military activity.

Grossi, director general of the International Atomic Energy Agency (IAEA), briefed the UN Security Council in New York on his proposals to ensure the safety of the plant.

The diplomat, who visited the plant in March, told ambassadors that "there should be no attack of any kind from or against the plant."

Grossi added that Zaporizhzhia "should not be used as storage or a base for heavy weapons," such as rocket launchers, artillery systems and munitions, tanks or military personnel.

He also said that "all efforts should be made to ensure that off-site power remains available and secure at all times."

And he added that "all structures, systems and components essential to the safe and secure operation" of the plant "should be protected from attacks or acts of sabotage."

"I respectfully and solemnly ask both sides to observe these five principles," said Grossi, adding that the IAEA intends to start monitoring the principles on-site.

"These principles are to no one's detriment and to everyone's benefit," he added.

Zaporizhzhia used to supply around 20 percent of Ukraine's electricity and continued to function in the early months of Russia's offensive despite frequent shelling, before halting power production in September.

None of its six Soviet-era reactors has since generated electricity, but the facility remains connected to the Ukrainian power grid for its own needs, notably to cool the reactors.