International Atomic Energy Agency (IAEA), the United Nations nuclear watchdog, has said that the drone attack at the Zaporizhzhia nuclear power plant (ZNPP) in Ukraine on Sunday is a “serious incident that endangered nuclear safety and security”.

Director General of the IAEA Rafael Mariano Grossi on Sunday night urged military decision-makers to abstain from any action violating the basic principles that protect nuclear facilities.

He said that such “reckless attacks significantly increase the risk of a major nuclear accident and must cease immediately”.

For the first time since November 2022, Europe’s largest nuclear power plant was directly targeted in military action that also represents a clear violation of the five basic principles for protecting the facility established by Director General Grossi at the United Nations Security Council in May last year, the IAEA said in a statement.

At this point, there are no indications of damage to critical nuclear safety or security systems at the site. However, the military strikes were another stark reminder of persistent threats to the ZNPP and other nuclear facilities during the armed conflict, despite the IAEA’s efforts to reduce the risk of a severe accident that could harm people and the environment in Ukraine and beyond, it added.

“The IAEA experts stationed at the site went to three affected locations and were able to confirm the physical impact of the drone detonations, including at one of the site’s six reactor buildings where surveillance and communication equipment appeared to have been targeted. While they were at the roof of the reactor, unit 6, Russian troops engaged what appeared to be an approaching drone. This was followed by an explosion near the reactor building,” the UN nuclear watchdog stated.

“The IAEA team reported that they observed remnants of drones at this and two other impact locations at the site. At one of them, outside a laboratory, they saw blood stains next to a damaged military logistics vehicle, indicating at least one casualty,” it added.

The experts reported hearing explosions and rifle fire on the site throughout the day. Additionally, the IAEA team heard several rounds of outgoing artillery fire from near the plant.

“While the team so far has not observed any structural damage to systems, structures, and components important to nuclear safety or security of the plant, they reported observing minor superficial scorching to the top of the reactor dome roof of Unit 6 and scoring of a concrete slab supporting the primary make-up water storage tanks,” the IAEA said.

Russia said that Ukraine was behind the attack, which it said injured three people. Ukraine has denied involvement.

The ZNPP is the largest nuclear power plant in Europe with a total capacity of 6 gigawatts. At the end of February 2022, the facility was taken under Russian control.