Russia and Ukraine have exchanged hundreds more prisoners as part of a major swap that amounted to a rare moment of cooperation in otherwise failed efforts to reach a ceasefire.

Russia launched its largest aerial assault of its three-year war on Ukraine overnight, targeting the capital and other regions with missiles and drones for a second night in a row, even as the two sides prepared to conclude a major prisoner exchange.

Reuters witnesses saw and heard successive waves of drones flying over Kyiv, and a series of explosions jolted the city.