UN nuclear watchdog chief Rafael Grossi said Saturday he would travel to Ukraine's Zaporizhzhia plant next week, warning of the "precarious" situation there.
Europe's largest nuclear power plant, which Russia captured a year ago, has been subject to frequent shelling in the area.
Grossi will be travelling to the plant for the second time since Moscow invaded Ukraine "to assess first-hand the serious nuclear safety and security situation at the facility," said the International Atomic Energy Agency (IAEA).
"Despite our presence at the site for seven months now, the situation at the Zaporizhzhia Nuclear Power Plant is still precarious," Grossi said in a statement.
"The nuclear safety and security dangers are all too obvious, as is the necessity to act now to prevent an accident," he added.
Grossi has proposed establishing a security zone around the site.
"I remain determined to continue doing everything in my power to help reduce the risk of a nuclear accident during the tragic war in Ukraine," he said.
A fresh team of IAEA experts will accompany Grossi, the agency having maintained a permanent presence at the plant since September.
The February rotation was delayed almost a month, the IAEA said, denouncing "the very challenging circumstances faced by the experts".
The plant has also suffered repeated electricity outages.
The plant needs a reliable electricity supply to ensure essential nuclear safety and security functions.
