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 a major attack on the Ukrainian capital Kyiv and killed at least 13 people in strikes across the country as the two sides released hundreds more prisoners on the second day of a major prisoner exchange.

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