"The UN must ensure the security of this strategic object, its demilitarisation and complete liberation from Russian troops," Zelensky said in a statement after meeting UN chief Antonio Guterres in Lviv.

The Ukrainian leader also criticised "deliberate" Russian attacks on the facility.

Ukraine and Russia have been accusing each other of targeting the Zaporizhzhia nuclear plant -- the biggest in Europe -- which Russia seized last March.

Tensions around the power plant have fuelled global fears of a nuclear disaster.

The two leaders also discussed grain exports, after a deal brokered by the UN and Turkey allowed their resumption this month.

Exports had been blocked following Russia's invasion of Ukraine.

"We agreed to continue the coordination of the grain initiative implementation. We also discussed the possible directions of its development," Zelensky said.

The first ship to depart under the deal left Ukraine on August 1. Since then, 25 cargo ships have sailed from Ukrainian ports.

Russia and Ukraine are two of the world's biggest grain exporters. The halt of exports led to price increases globally amid fears of widespread food shortages, particularly in poor countries.

Zelensky and Guterres also spoke about deportations of Ukrainians to Russia, and about the release of military staff and medics taken prisoner by Russia, according to Zelensky.