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

The Ukrainian capital has been struck by a large-scale Russian drone and missile attack that left at least 15 people injured, officials said. Explosions and machine gun fire were heard throughout Kyiv from Friday night into Saturday morning as many people sought shelter in subway stations.

Russia launched 250 drones and 14 ballistic missiles against Kyiv, Ukraine's air force said, causing fires in residential buildings. It was one of the biggest combined aerial assaults on the city since the war began. The air force said it had downed six missiles and 245 drones.