Ukraine and Russia carried out another exchange of prisoners of war as agreed in the 2 June Istanbul talks. Kyiv has not revealed how many Ukrainian defenders have been exchanged at each stage, saying only that the Thursday swap focused on severely wounded soldiers.

Since then, Russia and Ukraine have swapped dozens of prisoners of war, focusing on under-25s and the severely wounded and sick. There are hopes they could build into some of the biggest exchanges in the war that was triggered by Russia's 2022 invasion of Ukraine.

The number of Russian troops killed or wounded in Ukraine has topped 1 million, military officials in Kyiv said Thursday, describing the huge price that Moscow has paid for its 3-year-old invasion.