Ukraine on Wednesday carried out its biggest exchange of prisoners of war since Russia invaded, securing the release of 144 of its soldiers, including 95 who defended Mariupol's steelworkers, its military intelligence agency said.
Most of the prisoners were badly wounded, suffering from gunshot and shrapnel wounds, blast trauma, burns, fractured bones and amputated limbs, the GUR agency said on Telegram.
There was no comment from Russia about a prisoner swap.
But the leader of the self-proclaimed Donetsk People's Republic in eastern Ukraine, Denis Pushilin, said it had secured the release of 144 soldiers, including its fighters and those of the Russian army.
"We handed over to Kyiv the same number of prisoners from Ukrainian armed units, most of whom were wounded," Mr Pushilin said.
Hundreds more Ukrainians are still thought to be held by Russia and its pro-Moscow separatist proxies in eastern Ukraine, but their whereabouts are not known.
Kyiv has worried about the fate of hundreds of fighters from the Azov Brigades who played a prominent role in the defence of Mariupol and its Azovstal steelworks, before being encircled and eventually laying down their arms.
The prisoner swap included the handover of 43 members of the Azov Brigades, a National Guard unit that Russia says is a dangerous far-right battalion, in a promising sign for Ukrainians hoping for the release of other fighters from the unit.