The Liberia-flagged bulk carrier Arizona is seen in the sea port of Pivdenniy on August 8 after the resumption of grain exports.
UN Secretary-General Antonio Guterres will meet with the Ukrainian and Turkish presidents in Ukraine on August 18 and visit a Ukrainian Black Sea port the following day that has resumed shipments of grain exports halted by Russia's five-month-old invasion.
UN spokesman Stephane Dujarric said Ukrainian President Volodymyr Zelenskiy will join Guterres in Lviv, in western Ukraine, to discuss the security situation at a Russian-occupied nuclear power plant and possible paths out of the conflict with Russia.
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Guterres and the international community have expressed intense concerns over the risk of disaster at the Zaporizhzhya nuclear power plant, Europe's largest, amid reports of shelling and other dangers in the past week.
The United Nations has offered to help facilitate a visit by its International Atomic Energy Agency (IAEA) inspectors to Zaporizhzhya, but Moscow has dismissed a mission traveling through Kyiv despite vowing it would do all it could to help ensure IAEA access to the plant.
Zelenskiy earlier on August 16 accused Russia of "nuclear terrorism" in its actions while Moscow says Ukrainian troops are responsible for artillery fire near the facility.
Turkish President Recep Tayyip Erdogan has repeatedly sought a role for his NATO-member state to mediate in the conflict, and Ankara was crucial to a recent deal that allowed for the restart of grain and fertilizer exports from three of Ukraine's Black Sea ports.
Dujarric said Guterres on August 20 will visit the Joint Coordination Center in Istanbul that oversees the seaborne shipments.
The center is staffed by Russian, Ukrainian, Turkish, and UN officials.
The first ship to have left Ukraine under the multilateral deal two weeks ago was said by a shipping source and satellite data to have docked early on August 16 in the Syrian port city of Tartus.
The ship, the Sierra Leone-flagged Razoni, departed Ukraine on August 1 and didn't unload in Lebanon as scheduled but went dark before appearing in Tartus.
Russia is a key ally who has helped Syrian President Bashar al-Assad weather a brutal civil war and has a small naval facility at Tartus.
A UN-chartered ship loaded with 23,000 tons of Ukrainian grain meanwhile set sail on August 16 from a Black Sea port for Ethiopia, the first shipment of its kind in a program to assist countries facing famine, according to Ukraine's Infrastructure Ministry.