A planned exchange of Russian and Ukrainian prisoners of war failed to take place on Saturday, with Moscow accusing Kyiv of postponing the swap at the last minute, which Ukrainian officials dismissed as more “dirty games” from the Kremlin.

Russia claims Ukraine indefinitely postponed the release while Kyiv maintains it has been delayed until next week.

Air assaults on Saturday killed at least four people. Kharkiv’s mayor described an overnight strike as “the most powerful attack” since the beginning of the war.