KYIV — Two people were hospitalized following a 3½-hour Russian drone barrage on a port in Ukraine’s Odesa region on Sunday, officials said.

The attack on the Reni seaport comes a day before President Putin is due to meet with his Turkish counterpart, Recep Tayyip Erdogan, to discuss the resumption of food shipments from Ukraine under a Black Sea grain agreement that Moscow broke off from in July.

Russian forces fired 25 Iranian-made Shahed drones along the Danube River in the early hours of Sunday, 22 of which were shot down by air defenses, the Ukrainian air force said on Telegram.

President Zelensky’s chief of staff, Andriy Yermak, described the assault as part of a Russian drive “to provoke a food crisis and hunger in the world.”

Russia’s Defense Ministry said in a statement that the attack was aimed at fuel storage facilities used to supply military equipment.

Messrs. Putin and Erdogan’s long-awaited meeting is due to take place at Sochi on Russia’s southwest coast on Monday.

Turkish officials have confirmed that the pair will discuss renewing the Black Sea grain initiative, which the Kremlin pulled out of six weeks ago.

The deal — brokered by the United Nations and Turkey in July 2022 — had allowed nearly 36 million tons of grain and other commodities to leave three Ukrainian ports safely despite Russia’s war.

However, Russia broke away from the agreement after claiming that a parallel deal promising to remove obstacles to Russian exports of food and fertilizer hadn’t been honored.

Moscow complained that restrictions on shipping and insurance hampered its agricultural trade, even though it has shipped record amounts of wheat since last year.

The Sochi summit follows talks between the Russian and Turkish foreign ministers on Thursday, during which Russia handed over a list of actions that the West would have to take in order for Ukraine’s Black Sea exports to resume.

Mr. Erdogan has indicated sympathy with Mr. Putin’s position. In July, he said Mr. Putin had “certain expectations from Western countries” over the Black Sea deal and that it was “crucial for these countries to take action in this regard.”

Elsewhere in Ukraine, two people were killed and two others were wounded during Russian shelling Sunday on the village of Vuhledar in the Donetsk area.

Artillery fire hit eight settlements across the region, Ukraine’s National Police wrote on Telegram.

Ukrainian prosecutors also announced Sunday that they had opened a war crimes investigation into the death of a police officer killed by Russian shelling on the town of Seredyna-Buda on Saturday afternoon.

Two other police officers and one civilian were wounded during the attack, which hit Ukraine’s north-eastern Sumy region.