Russia has accused Ukraine of deliberately shooting down a Russian military transport plane carrying 65 captured Ukrainian soldiers to a prisoner exchange, with a local official saying all 74 people on board have been killed.
Russian state media said six Russian crew members and three guards were on the Ilyushin Il-76 military transport plane which was shot down near the Russian city of Belgorod near the Ukrainian border.
"It was absolutely deliberate," Andrei Kartapolov, a lawmaker in Russia's parliament and a retired general, said in a TV interview with the SHOT outlet.
"They knew very well that the plane was en route, where it was going and the operators of (Ukrainian) surface-to-air missile systems cannot mistake transport planes for military planes or helicopters as targets.
"It was done deliberately to sabotage the prisoner exchange."
Kartapolov, who still has close links to the defence ministry, said the plane had been shot down by three missiles of either United States or German manufacture.
If the details are confirmed, it would be the deadliest incident of the almost two-year-old war inside Russia's internationally recognised borders.
Ukraine's defence ministry did not immediately reply to a Reuters request for comment.
It was cited by the Interfax-Ukraine news agency as saying it did not have any reliable information for now but would share it when it did.
"Comments will come a little later," Mykhailo Podolyak, a Ukrainian presidential adviser, told Reuters.
"Time is needed to clarify all the data."
Video posted on the Telegram messaging app by Baza, a channel linked to Russian security services, and verified by Reuters, showed a large aircraft falling towards the ground near the village of Yablonovo in the Belgorod region and exploding in a vast fireball.
Reuters could not immediately verify details of who was on board, but Moscow and Kyiv have regularly swapped prisoners since Russia began what it calls its "special military operation" in Ukraine in February 2022.
Vyacheslav Gladkov, governor of Belgorod region, said everyone on board the plane had been killed and that the plane had come down in the region's Korochansky district, northeast of the city of Belgorod.
He said investigators and emergency workers were already on the scene.
The Belgorod region, which borders Ukraine, has come under frequent attack from Ukraine in recent months, including a December missile strike which killed 25 people.
Vyacheslav Volodin, chairman of the State Duma, the lower house of Russian parliament, said the chamber would prepare an appeal to the US Congress and the German Bundestag "so their lawmakers at last can see clearly who they are financing, who they are helping".
"They (Ukraine) shot down their own soldiers in mid-air," Volodin said.
"Their mothers, wives and children were waiting for them.
"They took a decision and shot down our defenceless pilots on a military transport plane, who were carrying out a humanitarian mission, with American and German rockets."
The Il-76 is a military transport aircraft designed to airlift troops, cargo, military equipment and weapons. It usually has a crew of five, and can carry up to 90 passengers.
The Kremlin said in response to a reporter's question that it was looking into the situation.
