Russia's defense ministry said it was only by luck that a radiation accident had been avoided after what it described as an artillery barrage.
"It is purely a security issue. Those who create nuclear threats to other nations are certainly not capable of using nuclear technologies safely."Ukrainian President Volodymyr Zelensky
Ukrainian President Volodymyr Zelensky though said Moscow was responsible and accused it of committing "an open, brazen crime, an act of terror."
In a late-night address, he demanded sanctions on the entire Russian nuclear industry.
"It is purely a security issue. Those who create nuclear threats to other nations are certainly not capable of using nuclear technologies safely," he said.
Russian defense ministry statement
The Russian defense ministry said the generating capacity of one unit had been reduced and the power supply to another had been cut. In addition, the nearby city of Enerhodar had power and water supply problems, it said.
"Fortunately, the Ukrainian shells did not hit the oil and fuel facility and the oxygen plant nearby, thus avoiding a larger fire and a possible radiation accident," a ministry statement said.
Enerhodar and the nearby nuclear plant were seized by invading Russian troops in early March, and are still close to the frontline.
US Secretary of State Antony Blinken on Monday accused Moscow of using the plant as a shield for its forces, and Ukraine has accused Russia of shelling its positions from positions near the power station.
Ukrainian foreign ministry statement
"The possible consequences of hitting an operating reactor are equivalent to the use of an atomic bomb," Ukraine's foreign ministry said on Twitter.
Artillery shelling of the territory near the ZNPP industrial site took place today. As a result of 3 recorded hits, the high-voltage power supply line of the ZNPP was damaged. The possible consequences of hitting an operating reactor are equivalent to the use of an atomic bomb.— MFA of Ukraine (@MFA_Ukraine) August 5, 2022
Ukraine's state nuclear power company, Energoatom, earlier said the plant was operational and no radioactive discharges had been detected. Two of the six reactors are still operating.
The Russian-installed administration of Enerhodar said on Friday that power lines at the plant had been cut by a Ukrainian artillery strike. The facility continues to be run by its Ukrainian technicians.
Reuters was unable to verify the battlefield reports.
Rafael Grossi, head of the International Atomic Energy Agency, said this week that contact with the plant was "fragile" and communications did not function every day. He appealed for access to determine whether it was a source of danger.