Russia and Ukraine exchanged prisoners of war under the age of 25 on Monday in emotional homecoming scenes, the first step in a series of planned prisoner swaps that could become the biggest of the war so far.

A prisoner exchange is under way between Russia and Ukraine, governments in Moscow and Kyiv have confirmed. Ukraine's President Volodymyr Zelensky said the exchange would unfold "in several stages" over the coming days, adding that the wounded, seriously wounded and soldiers under 25 were being returned.

The Russian Ministry of Defense said soldiers have advanced into the Dnipropetrovsk region in south-central Ukraine.