In a statement issued by his spokesperson, António Guterres expressed alarm over the dangerous escalation and the rising toll on civilians.

He reiterated that attacks against civilians and critical infrastructure are prohibited under international law and called for an immediate and unconditional ceasefire.

“These strikes disrupted the power supply to the Zaporizhzhia Nuclear Power Plant, once again underlining the ongoing risks to nuclear safety,” UN Spokesperson Stéphane Dujarric said.

“The Secretary-General reiterates his call for a full, immediate and unconditional ceasefire in Ukraine as a first step towards a just, comprehensive and sustainable peace, in line with the UN Charter, international law and relevant UN resolutions.”

Fragile situation

The airstrikes on Friday severed the nuclear plant’s last external power connection, forcing the ZNPP to rely on emergency diesel generators for more than three hours, according to the International Atomic Energy Agency (IAEA).

Power was eventually restored, but the incident marked the ninth time the plant has lost all off-site electricity since the full-scale invasion began in 2022.

Rafael Mariano Grossi, Director General of the nuclear watchdog, warned that the situation remains extremely fragile.

“What was once virtually unimaginable – that a major nuclear power plant would repeatedly lose all of its external power connections – has unfortunately become a common occurrence,” he said.

Nuclear safety deterioration

Located in southern Ukraine, the Zaporizhzhia plant is the largest nuclear power facility in Europe. Although its six reactors have been in cold shutdown since 2024, they still require electricity to cool reactor cores and spent fuel pools to prevent overheating and potential radioactive release.

During the blackout, 18 diesel generators were activated to maintain critical cooling functions. The plant has enough diesel on site for at least ten days, with contingency plans in place to secure further supplies if needed, IAEA reported.

The ZNPP has become dramatically more vulnerable since the war began. Prior to the conflict, it had access to ten external power lines; it now relies on just one.

IAEA teams remain based at the site and continue to monitor the situation closely.