The plant, Europe's largest with six reactors, was seized by Russian forces in the early weeks of Moscow's invasion of Ukraine. The facility has been cut off from external power since September 23 -- the 10th time the line has come down.
The plant produces no electricity, but fuel in its reactors is being cooled by emergency diesel generators. Rafael Grossi, director general of the International Atomic Energy Agency, said the external line had to be restored.
"Both sides say they stand ready to conduct the necessary repairs on their respective sides of the frontline. But for this to happen, the security situation on the ground must improve so that the technicians can carry out their vital work without endangering their lives," Grossi said in a statement.
"I'm calling on both sides to do what is necessary to prevent a further deterioration. It is a question of political will, not whether it is technically possible, which it is."
Russian President Vladimir Putin on Thursday warned Ukraine that it was playing a dangerous game by launching strikes near the plant.
Ukrainian Foreign Minister Andrii Sybiha accused Moscow of deliberately cutting the link in order to connect the station to its own grid.
In his statement, Grossi also said that an external power cutoff this week at the decommissioned Chornobyl nuclear power plant -- site of the world's worst civil nuclear accident in 1986 -- had lasted 16 hours.
He said the containment vessel erected in 2016 to prevent contamination had experienced a partial blackout and had no reserve power for three hours when a power line to the nearby town of Slavutych came down.
Ukrainian President Volodymyr Zelenskiy said Russia deliberately staged the attack that cut power to the station.Â
