On Tuesday, the head of the International Atomic Energy Agency (IAEA) said a drone had hit and severely damaged one of its official vehicles on the road to Ukraine's Zaporizhzhia nuclear power plant.

Nobody was injured in the attack, but Kyiv and Moscow have since traded blame over the strike.

Grossi on Thursday addressed the governing board of the Vienna-based IAEA, which held an emergency meeting at Ukraine's request to discuss its "unstable" energy infrastructure.

"On Tuesday, a drone hit a clearly marked IAEA vehicle which was completing the rotation of IAEA staff," Grossi told the extraordinary meeting.

"Whoever did this knew exactly what was being done. That convoy had three Ukrainian vehicles, then the vehicles of the IAEA and it was our vehicle which was hit," he said.

"It was a clear intention to harm us or to intimidate us. This was a direct attack," Grossi added, without apportioning blame.

While the rear of the armoured agency vehicle was completely destroyed, a driver and a security officer travelling on board were both physically unharmed.

The IAEA has a permanent presence at the Russia-controlled Zaporizhzhia atomic plant, which has become the target of repeated strikes.

Since Russia's invasion of Ukraine in 2022, Grossi has warned of the potential for a nuclear accident at the plant.

"This is not the first time that we have been confronting difficulties, but this one was particularly concerning," Grossi said, reiterating his calls for "maximum restraint".

In recent weeks, Moscow has stepped up bombardments of Ukraine's energy infrastructure.

Later on Thursday, the IAEA's 35-nation board of governors passed a resolution voicing "concern" over the danger posed by attacks on Kyiv's "vulnerable" energy infrastructure that have "further endangered nuclear safety".

The resolution brought by Ukraine was approved by 22 of the agency's board members, with two votes against it and 10 countries abstaining from the vote, diplomats told AFP.