Ukraine said Friday that Russia had returned the bodies of 77 soldiers, days after the crash of a Russian military transport plane threw doubt on the future of such exchanges.
Moscow and Kyiv traded fresh accusations over the plane that Russia says was shot down by Ukraine forces near the rivals' border, killing 65 Ukrainian prisoners of war.
While Kyiv has not denied the claims outright, officials have appeared to question whether its POWs were on board.
The latest repatriation of bodies appeared unrelated to the downing of the plane, which crashed in a fireball in Russia's western Belgorod region on Wednesday.
"Preparations for the repatriation had been underway for a long time," Ukraine's Coordination Headquarters for the Treatment of Prisoners of War said in a statement.
Hundreds of captured prisoners have been freed in dozens of exchanges throughout the nearly two-year war.
But Russia's claims that Ukraine shot down a plane ferrying Ukrainian detainees has thrown doubts on the future of such exchanges.
- Disputed evidence -
On Friday, Ukraine was still disputing Russia's account of how the Ilyushin 76 military transporter crashed.
The Kremlin dismissed the idea of releasing evidence proving that dozens of Ukrainian soldiers had been killed.
"Investigators are working, I have nothing to add on this topic," Kremlin spokesman Dmitry Peskov told reporters when asked if Russia planned to publish evidence on how Ukraine shot down the plane, and who was on board.
On Thursday, Russia's Investigative Committee published video footage of what it said was the crash site, showing a small chunk of plane debris and blurred close-ups of a body.
A second video published Friday showed more of the debris, a forensics team sealing up a body bag and photos of three identification documents it said were from dead victims.
It then published a blurry video purporting to show vehicles transporting the prisoners to the plane before it took off, but the quality was too poor to immediately verify this.
Ukraine's human rights ombudsman Dmytro Lubinets dismissed the material released so far by Moscow as "elements of an information propaganda campaign against Ukraine".
Kyiv and Moscow have opened criminal investigations, and Ukrainian President Volodymyr Zelensky has called for an international investigation.
On Wednesday, Zelensky accused Moscow of "playing with the lives" of Ukrainian soldiers and their families.
Kyiv has not confirmed nor denied its involvement in the crash, or said whether it was carrying captured Ukrainian soldiers.
It confirmed that a prisoner exchange was due to take place on Wednesday, but that Moscow had not informed Kyiv that the soldiers would be transferred by plane, as it had done in the past.