Russia and Ukraine carried out an exchange of prisoners of war on Monday involving POWs under the age of 25 and others who had been severely wounded, the start of what could become the biggest swap of the war so far.

The exchange, announced by both sides, was the result of direct talks in Istanbul on June 2 that resulted in an agreement to conduct an exchange of at least 1,200 POWs on each side and to repatriate thousands of bodies of those killed in the war.

The return of POWs and the repatriation of the bodies of the dead is one of the few things the two sides have been able to agree on, even as their broader negotiations have failed to get close to ending the war, now in its fourth year.

Ukrainian President Volodymyr Zelenskiy said his country had received the first group of prisoners from Russia and that it would take several days to complete the swap.

"Today's exchange has begun. It will be done in several stages in the coming days," Zelenskiy said on the Telegram app.

A still image from a video released by the Russian Defence Ministry shows what it said to be Russian service personnel captured by Ukrainian forces and released during the latest exchange of prisoners of war in the course of Russia-Ukraine conflict, as they board a bus at an unknown location in Bel (credit: REUTERS)
A still image from a video released by the Russian Defence Ministry shows what it said to be Russian service personnel captured by Ukrainian forces and released during the latest exchange of prisoners of war in the course of Russia-Ukraine conflict, as they board a bus at an unknown location in Bel (credit: REUTERS)

Neither side confirmed how many prisoners had been swapped

"The process is quite complex, with many sensitive details, and negotiations continue virtually every day. We count on the full implementation of the humanitarian agreements reached during the meeting in Istanbul. We are doing everything possible to bring back every single person."

Neither side said how many prisoners had been swapped on Monday, but the Russian Defence Ministry said in its statement that the same number of military personnel had been exchanged on each side.

Kremlin aide Vladimir Medinsky said over the weekend that the first list of 640 POWs had been handed to Ukraine.

The Russian military said its returned servicemen were now in Belarus, a close Russian ally, where they were getting psychological and medical assistance before being transferred to Russia for further care.

The Kremlin had said earlier on Monday that Russia was ready to honor agreements with Ukraine on the POW exchange and the repatriation of dead soldiers despite what it said was Kyiv's failure to fully honor its side of the bargain. Ukraine had denied allegations of postponing the prisoner swaps.