Russia and Ukraine accused each other Friday of shelling a prison in a separatist region of eastern Ukraine, an attack that reportedly killed dozens of Ukrainian prisoners of war who were captured after the fall of a southern port city in May.

Russia said Ukraine’s military used U.S.-supplied multiple rocket launchers to strike the prison in Olenivka, a settlement controlled by the Moscow-backed Donetsk People’s Republic. Separatist authorities and Russian officials said the attack killed 53 Ukrainian POWs and wounded 75.

The Ukrainian military denied making any rocket or artillery strikes in Olenivka, and said it only aims for Russian military targets. It accused the Russians of shelling the prison to cover up the alleged torture and execution of Ukrainians there.

Neither claim could be independently verified.

The Russian claims are part of an “information war to accuse the Ukrainian armed forces of shelling civilian infrastructure and the population to cover up their own treacherous action,” Ukraine’s military said.

Denis Pushilin, the leader of the internationally unrecognized Donetsk republic, said the prison held 193 inmates. He didn’t specify how many of them were Ukrainian POWs.

A Russian Defense Ministry spokesperson, Lt. Gen. Igor Konashenkov, described the strike as a “bloody provocation” aimed at discouraging Ukrainian soldiers from surrendering. He said Ukraine used the precision High Mobility Artillery Rocket System to hit the prison and eight guards were wounded.

Ukrainian forces are fighting to hold on to the remaining territory under their control in Donetsk, which together with neighboring Luhansk province makes up Ukraine’s mostly Russian-speaking Donbas region.

For several months of the war in Ukraine, Moscow has focused on trying to seize parts of the Donbas not already held by the separatists. Ukrainian authorities in the Donetsk region accused Russia on Friday of shelling civilian targets in Ukrainian-held areas.

“The fighting in the region has been intensifying by the day, and civilians must evacuate while it’s still possible,” Donetsk Gov. Pavlo Kyrylenko said. “The Russian army doesn’t worry about civilian casualties. They are pummeling cities and villages in the region.”

Kyrylenko later said one person was killed and five injured in Russian rocket strike on the city of Kramatorsk on Friday.

The POWS at the Donetsk prison included troops captured during the fall of Mariupol. They spent months holed up with civilians at a giant steel mill in the southern port city. Their resistance during a relentless Russian bombardment became a symbol of Ukrainian defiance against Russia’s aggression.

More than 2,400 soldiers from the Azov Regiment of the Ukrainian national guard and other military units gave up their fight and surrendered under orders from Ukraine’s military in May.

Scores of Ukrainian soldiers have been taken to prisons in Russian-controlled areas such as the Donetsk region, a breakaway area in eastern Ukraine which is run by Russian-backed separatist authorities. Some have returned to Ukraine as part of prisoner exchanges with Russia, but families of others have no idea whether their loved ones are alive, or if they will ever come home.

In other developments on Friday:

— President Volodymyr Zelenskyy visited one of Ukraine’s main Black Sea ports a week after a deal was struck with Russia, Turkey and the United Nations to create safe corridors for ships to export grains that have been trapped in the country since the war began five months ago. Workers were seen preparing terminals for grain exports, which are relied on by millions of impoverished people worldwide facing hunger. Zelenskyy said the shipments would begin with the departure of several vessels that were loaded but could not depart Russia invaded Ukraine on Feb. 24.

— The Ukrainian presidential office said that at least 13 civilians were killed and another 36 were wounded in Russian shelling over 24 hours. In the southern city of Mykolaiv, at least four people were killed and seven others were wounded when Russian shelling hit a bus stop. The Russian barrage also hit a facility for distribution of humanitarian assistance, where three people were wounded, officials said. Ukrainian officials also said at least four civilians were killed and another five were wounded in the eastern town of Bakhmut in the Donetsk region.

— An appeals court in Kyiv on Friday reduced to 15 years the life sentence of a Russian soldier convicted in the first war crimes trial since Russia invaded Ukraine. Critics had said the sentencing of Vadim Shishimarin, 21, was unduly harsh given that he confessed to the crime and expressed remorse. He pleaded guilty to killing a civilian and was convicted in May. His defense lawyer argued that Shishimarin shot a Ukrainian man on the orders of his superiors.

(AP)