A local resident buys food products over a shop counter Friday, lit by a candle, on the outskirts of Bakhmut, the site of the heaviest battle against the Russian troops in the Donetsk region, Ukraine. Efrem Lukatsky/Associated Press

KYIV, Ukraine — The Russian Defense Ministry said Saturday that Moscow has moved to suspend its implementation of a U.N.-brokered grain deal which has seen more than 9 million tons of grain exported from Ukraine and has brought down global food prices.

The ministry cited an alleged Ukrainian drone attack against Russia’s Black Sea Fleet ships moored off the coast of occupied Crimea, which Russia says took place early Saturday, as the reason for the move. Ukraine has denied the attack.

The Russian declaration came one day after U.N. chief Antonio Guterres urged Russia and Ukraine to renew the deal. Guterres also urged other countries, mainly in the West, to expedite the removal of obstacles blocking Russian grain and fertilizer exports.

The U.N. chief underlined the urgency of renewing the deal brokered by the United Nations and Turkey in July, which expires on Nov. 19, “to contribute to food security across the world, and to cushion the suffering that this global cost-of-living crisis is inflicting on billions of people,” his spokesman said.

Russia’s U.N. Ambassador Vassily Nebenzia has said that before Moscow discusses a renewal “Russia needs to see the export of its grain and fertilizers in the world market, which has never happened since the beginning of the deal.”

Earlier Saturday, Ukraine and Russia offered differing versions on the Crimea drone attack in which at least one Russian ship suffered damage in Sevastopol, a major port, on the Ukrainian peninsula annexed by Moscow in 2014.

The Russian Defense Ministry said a minesweeper had “minor damage” during an alleged pre-dawn Ukrainian attack on navy and civilian vessels docked in Sevastopol, which hosts the headquarters of Russia’s Black Sea Fleet. The ministry claimed Russian forces had “repelled” 16 attacking drones.

An adviser to Ukraine’s Interior Ministry claimed that “careless handling of explosives” had caused blasts on four warships in Russia’s Black Sea Fleet. Anton Gerashchenko wrote on Telegram that the vessels included a frigate, a landing ship and a ship that carried cruise missiles used in a deadly July attack on a western Ukrainian city.

In other developments on Saturday, Russian troops moved large numbers of sick and wounded comrades from hospitals in Ukraine’s southern Kherson region and stripped the facilities of medical equipment, Ukrainian military officials said as their forces fought to retake a province overrun by invading soldiers early in the war.

A view of a destroyed bridge across the Siverskyi-Donets river Saturday in the liberated town of Sviatohirsk, Donetsk region, Ukraine. Andriy Andriyenko/Associated Press

Kremlin-installed authorities in the mostly Russian-occupied region had previously urged civilians to leave the city of Kherson, the region’s capital – and reportedly joined the tens of thousands of residents who fled to other Russia-held areas ahead of an expected Ukrainian advance.

“The so-called evacuation of invaders from the temporarily occupied territory of the Kherson region, including from medical institutions, continues,” the General Staff of the Armed Forces of Ukraine said.

The military’s claims could not be independently verified. Ukrainian President Volodymyr Zelensky said in a video address that the Russians were “dismantling the entire health care system” in Kherson and other occupied areas.

“The occupiers have decided to close medical institutions in the cities, take away equipment, ambulances. just everything,” Zelensky said. “They put pressure on the doctors who still remained in the occupied areas for them to move to the territory of Russia.”

Kherson is one of four regions in Ukraine that Russian President Vladimir Putin illegally annexed last month and where he subsequently declared martial law. The others are Donetsk, Luhansk and Zaporizhzhia.

As Kyiv’s forces sought gains in the south, Russia kept up its shelling and missile attacks in the country’s east, Ukrainian authorities said Saturday. Three more civilians died and eight more were wounded in the Donetsk region, which has again become a front-line hotspot as Russian soldiers try to capture the city of Bakhmut.

Western analysts have long identified Bakhmut as an important target in Russia’s stalled eastern offensive, one that would pave the way for Moscow’s forces to threaten Sloviansk and Kramatorsk, the two largest Ukrainian-held cities remaining in the long-embattled Donbas region.

Donetsk and neighboring Luhansk province make up the Donbas. Pro-Russia separatists have controlled parts of both provinces since 2014.

In the northeastern Kharkiv region, where Russia’s troops retreated last month and Ukrainian troops clawed back broad swaths of territory, Russian shelling overnight wounded three civilians, the region’s Ukrainian governor said.

Local residents stand in line waiting for free bread from volunteers Friday in Bakhmut, the site of the heaviest battle against the Russian troops in the Donetsk region, Ukraine. Efrem Lukatsky/Associated Press

Gov. Oleh Syniehubov wrote on Telegram said that two women in their 40s and a 60-year-old man were wounded near Kupiansk, a town that served as a resupply hub for Russian forces before Ukrainian troops regained control.

In neighboring Luhansk province, Gov. Serhii Haidai said that Ukrainian forces have shelled the entire length of the Kreminna-Svatove highway, where the Russians set up their main line of defense after their withdrawal from the Kharkiv region.

A Russian shelling attack Saturday also hit “critical infrastructure” in Ukraine’s southern Zaporizhzhia region, the Ukrainian governor of the illegally annexed province said. Around a quarter of the region, including the local capital, also called Zaporizhzhia, remains under Ukrainian military control.

Writing on Telegram, Gov. Oleksandr Starukh later said an industrial building was struck and there were no casualties.

In the latest swap, 52 Ukrainians, including two former defenders of the Azovstal steel plant in Mariupol, were released Saturday as part of a prisoner exchange with Russia, according to Andriy Yermak, a senior official at Ukraine’s presidential office. The steelworks in that bombed-out port city now symbolize Ukrainian resistance.

Among those released were the head of the surgical department of the military hospital at Mariupol, who was at Azovstal, and a young military surgeon, Yermak said.

Also released, he said, was a sailor who defended Ukraine’s Snake Island, a strategic Black Sea outpost seized by Russia in the opening hours of the war. Others coming home were Ukrainian soldiers captured by Moscow near the Chernobyl nuclear power plant – the site of the world’s worst nuclear disaster in 1986 – which Russian forces briefly occupied from February to March.

This version has been corrected to show the Russian Defense Ministry said one ship, not two, was slightly damaged in Crimea port.