At least four people were killed overnight and on Saturday morning as Russia continued to pound Ukraine with hundreds of drones and cruise missiles as part of a stepped-up bombing campaign that has further dampened hopes for a breakthrough in efforts to end the more than three-year-old war.

Russia fired 597 drones and decoys, along with 26 cruise missiles, into Ukraine overnight into Saturday, Ukraine's air force said.

Ukrainian air defence units shot down 25 missiles and 319 Shahed drones and jammed 258 other drones with electronic warfare, the air force said.