"Ukraine's Zaporizhzhia Nuclear Power Plant (ZNPP) has once again lost the connection to its last remaining main external power line, but the facility is continuing to supply electricity to the grid through a reserve line, the International Atomic Energy Agency (IAEA) was informed at the site today," the agency said in a statement.

"Less than 48 hours after Director General Rafael Mariano Grossi on Thursday established the presence of the IAEA Support and Assistance Mission to ZaporizhzhIa (ISAMZ) at the facility in southern Ukraine, the Agency's experts were told by senior Ukrainian staff that the ZNPP's fourth operational 750 Kilovolt (kV) power line was down. The three others were lost earlier during the conflict," it added.

Alarm has grown in recent weeks over shelling hitting the area of Europe's largest nuclear plant, Zaporizhzhia.

Ukraine on Friday said it bombed a Russian base in the nearby town of Energodar, destroying three artillery systems as well as an ammunition depot.

Russia's envoy to Vienna, Mikhail Ulyanov, said six IAEA inspectors would stay behind for several days and that two more would remain there "on a permanent basis".