The intensifying use of drones against civilians and humanitarian workers is a dangerous obstacle for aid operations in Ukraine, the UN's humanitarian chief, Tom Fletcher, said on Wednesday.

Fletcher spoke to the Associated Press news agency in an interview after a visit to the southern city of Kherson, where he witnessed how communities are coping while living under the constant threat of Russian drone strikes.

Fletcher described the visit to Kherson, split by the Dnipro River which acts as an active front line, as “quite chilling."

Russian forces occupy the eastern bank, while Ukrainian forces hold the western bank. From across the water, surveillance and exploding drones routinely hunt and attack civilians, vehicles and public transit.

“It really gives us an insight into the dangers ahead of us,” he said.