Hours later, Russia launched a glide bomb and a drone at the front-line town of Kostyantynivka in eastern Ukraine, killing four civilians and injuring a fifth, the prosecutor’s office said. The drone struck a car in which a married couple were travelling, killing the 39-year-old woman and 40-year-old man on the spot, it said.

Ukraine said it struck a Russian airbase on Saturday, while Russia continued to pound Ukraine with hundreds of drones overnight as part of a stepped-up bombing campaign that has further dashed hopes for a breakthrough in efforts to end the more than 3-year-old war.

Russia pummeled Kyiv with the largest drone attack of the war, hours after President Donald Trump spoke to Russia's Vladimir Putin, officials said.