(Reuters) -Ukraine's Foreign Ministry denounced on Friday what it described as Russian attacks on substations critical to supplying external power for Ukraine's nuclear power stations.
Russia has carried out "targeted strikes on such substations", a ministry statement issued late on Friday said.
"Deliberate strikes on civilian energy facilities that directly affect the safe operation of nuclear installations bear the hallmarks of nuclear terrorism and constitute a grave violation of international humanitarian law," it added.
The ministry referred to a statement issued on Thursday by the U.N. nuclear watchdog, the International Atomic Energy Agency, reporting military activity "that has led to damage to substations critical to nuclear safety and security in Ukraine".
The IAEA statement reported incidents near two nuclear plants - South Ukraine and Khmelnitskyi - that led to each plant losing access to an external power line.
A third station at Rivne had been forced to reduce power at two of its four reactors, the IAEA statement adds.
It gave no indication of which side might have been behind the incidents.
Russia and Ukraine regularly accuse each other of engaging in military activity that compromises safety at Ukraine's four working nuclear plants, particularly the Zaporizhzhia station.
Russian forces seized the Zaporizhzhia plant, Europe's largest with six reactors, in the early weeks of the February 2022 invasion of Ukraine.
The IAEA statement referred to continuing efforts to reconnect the second of two external power lines to the Zaporizhzhia plant, vital to keep nuclear fuel cool and guard against meltdowns. The plant generates no power at the moment.
There was no Russian reaction to the IAEA or the Ukrainian statements.
Both external links to the Zaporizhzhia plant were down for about 30 days in September and October, forcing officials to rely on emergency diesel generators. Kyiv and Moscow accused each other of causing the outage and disrupting efforts to fix it.
(Reporting by Ron Popeski; Editing by Himani Sarkar)
