The largest complex of its kind in Europe, Ukraine's Zaporizhzhia nuclear power plant is situated in a southern region seized by Russian invaders in March and now targeted by Ukraine for a counter-offensive.
United Nations chief Antonio Guterres told a news conference in Japan, where he attended the Hiroshima Peace Memorial Ceremony on Saturday to commemorate the 77th anniversary of the world's first atomic bombing, that "any attack (on) a nuclear plant is a suicidal thing,"
The U.N.'s Guterres said IAEA personnel needed access to Zaporizhzhia to "create conditions for stabilization".
Ukraine blamed Russia for weekend attacks in the area of the complex, which is still run by Ukrainian technicians. It said three radiation sensors were damaged, with two workers hospitalized with shrapnel injuries.
Yevhenii Tsymbaliuk, Ukraine's ambassador to the International Atomic Energy Agency (IAEA), said Zaporizhzhia staff were "working under the barrels of Russian guns". He called for a U.N.-led international mission to the plant by the end of August and accused Russia of trying to cause blackouts along Ukraine's southern electricity grid by targeting the plant.
The Russian defense ministry meanwhile said Ukrainian attacks had damaged high-voltage power lines servicing the Soviet-era plant and forced it to reduce output by two of its six reactors to "prevent disruption". read more
A Russian-installed official in the Zaporizhzhia region earlier said the facility was operating normally.
Reuters could not verify either side's version of what happened.
Kyiv appealed for the area to be demilitarized and for the International Atomic Energy Agency, the U.N.'s nuclear watchdog, to be let in. Russia's foreign ministry said it too favored an IAEA visit, which it accused Ukraine of blocking while trying to "take Europe hostage" by shelling the plant.
Ukraine has said it is planning to conduct a major counter-offensive in the Russian-occupied south, apparently focused on the city of Kherson, west of Zaporizhzhia, and that it has already retaken dozens of villages.
Petro Kotin, head of Ukraine's state nuclear power company Energoatom, called for peacekeepers to be deployed in and run the Zaporizhzhia site, with operational control handed back to Ukraine.
He flagged the danger of shells hitting containers of highly radioactive spent nuclear fuel as especially dire. If two or more containers were broken, "it is impossible to assess the scale" of the resulting disaster.
"Such insane actions could leave to the situation spiralling out of control and it will be a Fukushima or Chornobyl," Kotin said.
"Any attack (on) a nuclear plant is a suicidal thing," Guterres told a news conference in Japan, where he attended the Hiroshima Peace Memorial Ceremony on Saturday to commemorate the 77th anniversary of the world's first atomic bombing.
The world's worst civil nuclear disaster occurred in 1986 when a reactor at the Chornobyl complex in northwest Ukraine exploded. Soon after this year's Feb. 24 invasion Russian troops occupied that site, withdrawing from the area in late March.