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.

Ukraine denied Russian allegations on Saturday that it had indefinitely postponed prisoner swaps, accusing Moscow of "playing dirty games" after overnight Russian missile and bomb strikes on Kharkiv left three people dead and 22 injured.

One of the bombs hit the Children's Railway, a popular gathering place for families in central Kharkiv, Governor Oleh Syniehubov said.