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

UN aid chief Tom Fletcher said drone attacks in Ukraine are hindering relief operations. He warned that weak accountability and a USD 2 billion funding gap could worsen winter suffering.

The U.N.'s humanitarian chief warns of the growing threat of drones against civilians and aid workers in Ukraine.