US President Donald Trump announced on Friday a “major” prisoner swap between Russia and Ukraine, which would be the largest in three years of war.
Kyiv and Moscow are due to swap 1,000 people each in a deal agreed at talks in Istanbul last week, but a senior official with knowledge of the matter said the exchange had not yet happened.
Trump’s efforts to broker a ceasefire in Europe’s deadliest conflict since World War II have thus far been unsuccessful, despite his pledge to rapidly end the fighting.
The warring countries have held regular exchanges since Russia launched its 2022 invasion — but none have been of this scale.
Trump said on his Truth Social platform that the swap had been “completed”, but an official said the exchange — usually kept secret until it is finished and taking several hours — was ongoing.
“The process is ongoing and the exchange itself has not yet taken place,” the senior official with knowledge of the matter told AFP.
Trump also said: “This could lead to something big???”
After 39 months of fighting, thousands of POWs are held in both countries.
Russia is believed to have the larger share, with the number of Ukrainian captives held by Moscow estimated to be between 8,000 and 10,000.
Kyiv and Moscow have both accused each other of violating the Geneva Convention on the treatment of POWs, with the UN saying prisoners on both sides have been “subjected to torture and ill-treatment.”
Russia regularly violates international norms by putting POWs on trial — with allegations of torture widespread and several Ukrainian captives confirmed to have died in custody.
Moscow’s forces are also believed to have taken an unknown number of Ukrainian civilians into Russia in three years of seizing Ukrainian towns and cities.
There have been several high-profile cases of Ukrainian civilian captives.
Moscow this year returned the body of journalist Viktoria Roshchyna, who died in captivity.
Ukrainians put on trial have told Russian courts they experienced and witnessed torture in Russia’s notorious prison system.