'Very delicate equilibrium' at Ukraine's Zaporizhzhia nuclear plant, IAEA chief warns ahead of visit

The chief of the United Nation's atomic energy watchdog warned Tuesday that there's "no place for complacency" in security at the Russian-held Zaporizhzhia nuclear plant in Ukraine.

"There is absolutely no place for complacency or to believe that everything is stabilised there. Far from it," Rafael Grossi, director general of the International Atomic Energy Agency, told Ukrainian President Volodymyr Zelenskyy in Kyiv on Tuesday, according to a press release.

The energy chief is scheduled visit to the Zaporizhzhia Nuclear Power Plant -- the largest nuclear plant in Europe -- on Wednesday.

The plant has been under Russian control since March 2022. The plant is located on the banks of the Dnipro River in the country's southeast. It continues to be run by Ukrainian staff and has suffered many outages and even shelling since the war began.

Grossi had met earlier on Tuesday with the country's energy officials. The IAEA has continued to have a "general concern" about the amount of staffers running the facility, Grossi said during a press conference in Ukraine on Tuesday.

Prior to the war, the facility maintained a staff of about 12,000, according to the IAEA. But that's been cut to between 2,000 and 3,000 workers, the agency said.

"As I was saying just now, the facility is not producing energy, but still, there is a need to have a minimum number of people, ensuring a number of functions," Grossi said. "So, so far, the situation is stable, but it is a very, very delicate equilibrium."

He added that it was "very near" the minimum necessary staffing.

"So this is why I need to see by myself what is the situation, what are the prospects in terms of staffing," he said.

Russian nuclear officials have said they plan to add staff, he said.

ABC News' Nadine El-Bawab and Will Gretsky contributed to this report.