Russia's Defence Ministry and the head of Ukraine's presidential administration said the two countries had swapped 50 service personnel on Thursday in the latest prisoner exchange between the two sides.
Earlier on Thursday, the top Russian-installed official in Ukraine's partly-occupied Donetsk region said Moscow and Kyiv would each hand over 50 prisoners of war.
Andriy Yermak, head of Ukraine's presidential administration, reported the release of 50 "protectors of Ukraine" and said that the exchanges of prisoners of war would continue "until the liberation of the last Ukrainian".
"The defenders of Mariupol and Azovstal have returned, also those captured ... in the battles in the Donetsk, Luhansk and Zaporizhzhia directions," Yermak wrote on the Telegram messaging app.
Russia said it would fly its released prisoners to Moscow for medical checks and rehabilitation.
Yermak also said an unspecified number of Ukrainian prisoners of war who were released on Thursday had been kept in the Olenivka detention centre.
Dozens Of Ukrainian prisoners held by Moscow-backed separatists in the eastern frontline town of Olenivka, near Donetsk, were killed in an attack in July.
(Reporting by Reuters; Editing by Kevin Liffey, Conor Humphries and Mark Heinrich)
