Moscow and Kyiv said on Thursday they had exchanged 20 soldiers each in their latest prisoner swap.

"Another exchange of prisoners, another moment of joy," Ukrainian presidential aide Andriy Yermak said on Telegram. "We have managed to free 20 people."

They were "14 soldiers of Ukraine's army, four members of the territorial defence, a member of the national guard and a member of Ukraine's navy," said Yermak.

There were also "people that the Russians detained in Olenivka prison and in the temporarily occupied areas of the Zaporizhzhia and Kherson regions", he added.

Yermak posted two photos and a short video of the released prisoners in military uniform sitting on a bus, saying the freed soldiers were undergoing medical examinations.

Russia's defence ministry said in a statement on Telegram: "Twenty Russian soldiers have returned from Ukrainian territory controlled by Kyiv" and were getting the medical and psychological help they needed.

Russia and Ukraine last exchanged prisoners on Tuesday, with Kyiv saying 32 of its soldiers had been freed. (AFP)