(Bloomberg) -- Russia accused Ukraine of shooting down a military plane it said was carrying 65 Ukrainian prisoners for an exchange.

The IL-76 aircraft crashed in Russia’s Belgorod region on Wednesday, killing everyone on board, including six crew and three Russian soldiers, the Defense Ministry in Moscow said in a statement. Russian radar systems tracked the launch of two surface-to-air missiles from the nearby Ukrainian region of Kharkiv, it said. 

Ukraine’s armed forces said Russia was using the Belgorod airfield to intensify attacks on Kharkiv region and vowed to “continue to take measures to destroy the means of delivery and control the airspace.” Officials didn’t comment directly on whether Ukrainian troops downed the plane. 

Earlier, the Ukrainskaya Pravda news website reported that the military believed the Russian plane was carrying a consignment of S-300 air-defense missiles.

A senior Russian lawmaker, Andrey Kartopolov, head of the defense committee, earlier told the lower house of parliament that Ukraine shot down the plane using either US Patriot or German-made IRIS-T missiles. A second IL-76 plane with another 80 Ukrainian prisoners on board turned around and escaped attack, he said.

An investigation team was sent to the crash site, the state-run news service Tass reported, citing the Russian Defense Ministry.

A prisoner swap on the Ukrainian-Russian border was planned for Wednesday, and the Ukrainian side knew the prisoners would be brought by military aircraft to Belgorod’s airport, the ministry said. Ukrainian officials confirmed a prisoner exchange had been scheduled to take place that day.

“As of now, we don’t have reliable and comprehensive information about who was on the plane and how many,” Ukraine’s military intelligence service said in a website statement. “According to the accord, it was Russia that had to ensure the security of our war prisoners. At the same time, the Ukrainian side was not informed about the need to ensure air-space safety near Belgorod at a specific point in time, as was done many times previously.”

The intelligence agency said that could “indicate deliberate actions by Russia aimed at creating a threat to the lives and safety of the prisoners.”

Ukraine and Russia exchanged almost 500 prisoners earlier this month, the largest swap since the February 2022 invasion began. Ukraine handed over 248 Russian prisoners for 230 Ukrainian servicemen and civilians, according to announcements by both sides that also highlighted mediation by the United Arab Emirates in the negotiating process. 

Over the past week, Russia attacked Kharkiv region 19 times with more than two dozen missiles, killing 16 people, wounding 78, and destroying residential and other civilian buildings, Ukraine’s army said in its statement. 

--With assistance from Daryna Krasnolutska.

(Updates with Ukrainian intelligence statement in the eighth and ninth paragraphs.)

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