Ukraine has received the bodies of 140 soldiers killed while trying to defend the regions of Donetsk, Luhansk, Zaporizhzhya and Kherson from Russian attacks.
The authority responsible for prisoner of war matters said on Telegram on Friday.
Five bodies were from the Sumy section in northern Ukraine.
Russia has no Ukrainian territories under its control in this area, however at the beginning of March, units of allegedly Russian volunteers fighting on the side of Ukraine made advances from the Sumy region into Russian territory.
Once the identities of the dead have been established, they will be handed over to their relatives, the authority said.
The authority, known as the Coordination Headquarters for the Treatment of Prisoners of War, thanked the International Committee of the Red Cross for arranging the return.
Ukraine has been fending off a Russian invasion for over two years.
In spite of the ongoing fighting, both sides regularly exchange the bodies of fallen soldiers and prisoners of war.
It is not yet known whether and how many dead soldiers Russia has received in return.
