Russia battered Ukraine overnight with its largest drone attack since the war began, Ukraine’s military said Sunday, ahead of an expected phone call between US President Donald Trump and Russian President Vladimir Putin on ending hostilities.

Russia and Ukraine began a major prisoner exchange Friday, swapping hundreds of soldiers and civilians in the first phase of an exchange that was a moment of cooperation in otherwise failed efforts to reach a ceasefire in the 3-year-old war.

As Ukrainian drones strike deep into Russian territory, they are disrupting day-to-day life and reminding Russians that the war is not confined to the trenches.

Ukraine and Russia accused each other of launching attack drones on one another overnight, hours after Russian President Vladimir Putin spoke by phone with his US counterpart Donald Trump - and again refused an immediate ceasefire.

Russia launched its largest drone attack on Ukraine since the start of the war, before President Donald Trump is due to discuss a proposed ceasefire with Vladimir Putin.

The hourslong raids, involving hundreds of drones, were a reminder that any diplomatic resolution to the conflict remains far off.