KYIV - A backup power line to the Russian-held Zaporizhzhia nuclear power plant (ZNPP) inside Ukraine has been restored, providing it with the external electricity it needs to cool its reactors, the International Atomic Energy Agency said on Sunday.

“After yesterday’s restoration of (the) power line ... #ZNPP operator this morning shut down its last operating reactor, which over past week had been providing ZNPP w/ required power after it was disconnected from grid,” the IAEA said on Twitter.

“This power can now come from the grid instead.”

Operations at the plant had been stopped as a safety measure, Energoatom, the state agency in charge of the plant, said earlier on Sunday.

The plant "is completely stopped" after the agency disconnected the number 6 power unit from the grid at 3.41am local time, it said in a statement.

"Preparations are underway for its cooling and transfer to a cold state."

Last Wednesday, Kyiv called for residents of Russian-occupied areas around the plant, Europe's largest, to evacuate for their own safety.

Russia and Ukraine accuse each other of shelling the nuclear plant, risking a nuclear disaster.

Ukrainian President Volodymyr Zelensky has called for the surrounding area to be demilitarised.

Energoatom said that on Saturday it restored to operational capacity a communications line to the power system, which it said had been damaged by Russian shelling, allowing the plant to be powered by Ukraine's energy system.

"Therefore, a decision was made to shut down power unit No. 6 and transfer it to the safest state - cold shutdown," it said.

It said the risk of further damage to the line "remains high", which would force the plant to be "powered by diesel generators, the duration of which is limited by the technological resource and the amount of available diesel fuel". REUTERS