A public message broadcasted by the city of Seoul asked the public to refrain from touching balloons "identified in the sky near Seoul" and to report them as these were "being handled by the military".
Other regional governments had been asked to broadcast similar messages, the defence ministry said.
North Korea has said the balloons were retaliation for an ongoing propaganda campaign by North Korean defectors and activists in South Korea, who send balloons containing anti-Pyongyang leaflets, food, medicine, money and USB sticks loaded with K-pop music videos and dramas across the border.
Published 01 June 2024, 12:58 IST