Last week, Kiev and Moscow blamed each other after a fire broke out in a power plant's cooling tower.
The IAEA did not say who carried out Saturday's strike, but an IAEA team based in Zaporizhzhia said the damage appeared to have been caused by a drone carrying explosives.
“The team heard frequent explosions and repeated machine gun and rifle fire and artillery fire at various distances from the factory,” the agency said in a statement.
The plant has not produced power for more than two years, and all six reactors have been in a cold shutdown state since April.
Russia launched a full-scale invasion of its neighbor in February 2022 and has recently made slow progress in seizing more territory in eastern Ukraine.
But the Ukrainian military was shocked when it infiltrated the Kursk region, where it had been holding its ground for about two weeks.
Thousands of Russians were evacuated from the area.
On Sunday, Ukrainian Air Force Commander Mykola Oleshchuk said his troops had destroyed a second bridge in the Kursk region, “depriving the enemy of his logistics capabilities.”
Earlier this week, Ukraine destroyed a bridge over the Sayim River that the Kremlin used to supply its military.
This is the first time that foreign troops have entered Russian territory since World War II.
