The bodies of some Ukrainian fighters killed defending the key south-eastern port of Mariupol have arrived in Kyiv, the soldiers' families say.
They say this was part of a swap with Russia, with each side receiving 160 bodies. Moscow has not commented.
The fighters spent weeks holed up in the city's Azovstal steelworks. In May, the survivors were taken prisoner.
More than 1,000 Ukrainian soldiers captured in Mariupol have reportedly been transferred to Russia.
The soldiers, who were being held in locations controlled by Russian-backed forces in eastern Ukraine, were moved to Russia for investigation, a Russian law enforcement source told Itar-Tass, a state-owned Russian news agency.
The same source said more prisoner transfers would follow.
There has been no confirmation from the Ukrainian side, but previously Ukraine's President Volodymyr Zelensky said he thought more than 2,500 Azovstal defenders - who also include border guards, police and territorial defence - were being held by Russia.
Kyiv says Mariupol's last defenders were given orders to save their lives after successfully completing their main goal of holding up Russian troops and not allowing them to be redeployed to other key battlefields.
Moscow says the Ukrainian defenders were forced to surrender.
Mariupol was captured by Russia in May after a months-long siege and heavy shelling that virtually wiped out the city. Ukrainian officials estimate that tens of thousands of people, including children, may have been killed.
They have also been warning of a possible outbreak of cholera in the city, where many bodies are still believed to be buried under the rubble, and sewage has reportedly contaminated main water supply chains.
After Mariupol, Russian forces turned their attention to Severodonetsk - and the twin city of Lysychansk. Seizing them would give the Russians control of the Luhansk region - which, alongside Donetsk, makes up the wider Donbas, stated target of Russian operations.
Fate of fighters unknown
In a post on Telegram late on Monday, the Ukrainian fighters' families said "the bodies of the killed Azovstal defenders" had arrived in the capital Kyiv.
They said that one-third of those were fighters from the Azov regiment, and that the identification process was continuing and could take up to three months.
Russia has not officially confirmed the exchange of bodies.
However, Russian war correspondent Irina Kuksenkova on Friday reported that the exchange did take place on the line of contact between Ukrainian and Russian forces in the southern Zaporizhzhia region. She said each side received 160 bodies.
President Zelensky has said Ukraine's intelligence officials were working on a plan to secure the release of the surviving fighters, without giving any further details.
Kyiv wants them all handed over, but several leading Russian lawmakers are demanding that some of the soldiers - specifically from the Azov regiment - should be put on trial.
The regiment was set up in 2014, with some of its members initially linked to far-right groups. Kyiv says the unit has since been reformed and is now outside politics.
President Vladimir Putin has repeatedly stated that his "special military operation" launched on 24 February was to de-Nazify and de-militarise Ukraine. He provided no evidence to back his claims, but officials have often mentioned the Azov Regiment.
In Ukraine, however, many people regard Azov soldiers as national heroes fighting what they say is in fact the neo-Nazi regime of President Putin.