The bodies of some Ukrainian fighters killed defending the key south-eastern port of Mariupol have now 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.
On the Ukrainian side, more than 50 bodies were those of members of the Azov regiment, the families say.
The Ukrainians were holed up in the Azovstal steelworks for weeks. In May, the survivors were taken prisoner.
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. They were later moved to at least two locations controlled by Russian-backed forces in eastern Ukraine.
Mariupol was captured by Russia in May after a months-long siege and heavy shelling that killed many civilians, including children.
More than 2,500 Azovstal defenders – who also include border guards, police and territorial defence – are currently being held by Russia, Ukrainian President Volodymyr Zelensky says.
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.
The families added that talks were ongoing on further prisoner swaps, without giving any further details.
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.
On Monday, President Zelensky said he believed that more than 2,500 Azovstal fighters were still in Russian custody.
“It’s difficult to say more precisely,” he was quoted as saying by Ukraine’s Ukrinform news agency.
He added that Ukraine’s intelligence officials were working on a plan to secure the release of the 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.
Russia describes Azov regiment fighters as neo-Nazis – a claim denied by Ukraine, who says the unit has been reformed and is outside politics.
Many Ukrainians regard Azov soldiers as national heroes fighting what they say is the neo-Nazi regime of Russian President Vladimir Putin.