STORY: IAEA chief Rafael Grossi said the mission was aware of the high risk "increased military activity in the area" between Ukrainian and Russian defense lines posed but was pressing ahead with its plan to visit the facility and meet its staff.

"We are going to be liaising and consulting with the staff at the facility. And I am going to consider the possibility of establishing a continued presence of the IAEA at the plant, which we believe is indispensable to stabilize the situation," Grossi told reporters before the mission set off.

Russian-installed officials have suggested that the team from the U.N. nuclear watchdog would have only a day to inspect the plant, while the mission is preparing for longer. The mission arrived in Zaporizhzhia, 34 miles from the plant, on Wednesday (August 31) and Ukraine's defense ministry said it was scheduled to visit the facility on Thursday.

Conditions at the Zaporizhzhia nuclear plant, Europe's largest, have been unraveling for weeks, with Moscow and Kyiv trading blame for nearby shelling and fueling fears of a radiation disaster.