The head of the International Atomic Energy Agency says "powerful explosions" have shaken the area of the Zaporizhzhia nuclear power plant in southern Ukraine.

IAEA Director General Rafael Grossi said in a statement that the explosions occurred on Saturday evening and Sunday morning.

An IAEA team at the plant reported that more than a dozen blasts were heard within a short period of time on Sunday morning "in what appeared to be renewed shelling" close to and at the plant site.

The team said some buildings, systems, and equipment at the site had been damaged. But it added that none of the damage had so far been critical for nuclear safety and security.

Grossi said the explosions abruptly ended "a period of relative calm" at the facility. He said whoever is behind the blasts must stop the acts immediately.

Grossi said he is "not giving up" efforts to set up a nuclear safety and security zone around the plant.

In recent months, the IAEA has engaged in consultations with Ukraine and Russia to establish such a zone. But no agreement has materialized yet.

The Zaporizhzhia plant is one of the largest nuclear power stations in Europe. Russia seized control of the facility in the early stages of the invasion of Ukraine.

Workers restored external power to the plant every time shelling at the site and nearby areas cut the supply. The external power is used to cool reactors.