N.Korean rubbish balloons disrupt flights in Seoul

North Korea has sent about 500 balloons laden with rubbish into South Korea's air space in 24 hours, officials in the South say, disrupting flights and igniting a fire on the roof of a residential building.

The balloons are part of an ongoing propaganda campaign by Pyongyang against North Korean defectors and activists in the South, who regularly send balloons carrying items such as anti-Pyongyang leaflets medicine, money and USB sticks loaded with K-pop videos and dramas.

A suspected balloon suspended take-offs and landings at Seoul's Gimpo Airport on Wednesday evening for two hours, an official at the Korea Airports Corporation said.

Balloons have affected traffic at South Korea's main international airport, Incheon, several times in recent weeks.

In Gyeonggi, a province near Seoul, a balloon caught fire on top of a residential building.

Firefighters extinguished the blaze, the Gyeonggi Northern Fire and Disaster Headquarters said.

South Korea's military said some rubbish balloons were equipped with timed poppers that could cause fires.

"A timer is attached to the trash balloons, which has the effect of popping the balloons and spreading the trash after a certain period of time has passed," Lee Sung-jun, a spokesman for South Korea's Joint Chiefs of Staff, told a briefing.

Lee said 480 balloons had landed mostly carrying paper and plastic in South Korea as of Thursday.

On Wednesday, North Korean balloons had landed near the heavily guarded presidential office in Seoul.