Trash balloons land near S Korea president's office

File photo of one of many trash balloons that have landed in South Korea over the past few weeks

Balloons carrying rubbish sent by North Korea have landed in South Korea's presidential compound in the capital city of Seoul, say officials.

It is the first time the South Korean leader's office, which is a designated no-fly zone, has been hit by balloons launched by Pyongyang.

A chemical, biological and radiological warfare response team was sent to collect the balloons, the presidential security service said.

They were found to pose no contamination or safety risk.

According to a news report by local news site Yonhap, the military did not shoot down the balloons as they feared it would cause their contents to spread further.

The balloons also landed in other parts of Seoul, with officials telling residents to avoid touching the balloons and to "report them to the nearest military unit or police station".

South Korea's Joint Chiefs of Staff told Reuters that with wind blowing from the west, balloons aimed at the South were likely to land in the northern Gyeonggi province, the country's most populous province, where the capital city is located.

The latest incident comes days after South Korea's military reacted to the escalating launches by restarting propaganda broadcasts from loudspeakers along the border.

Balloons spotted floating above the South Korean presidential compound in Seoul on Wednesday

North and South Korea have both used balloons in their propaganda campaigns since the Korean War in the 1950s.

The launches have escalated this year, with thousands of balloons being sent by the North across the border since May.

Wednesday's balloons marked the North's tenth launch this year, in what it claims is retaliation for balloons sent by South Korean activists.

These allegedly contained anti-Pyongyang leaflets, alongside food, medicine, money and USB sticks loaded with K-pop videos and dramas.