Seoul: N Korean trash balloon landed on S Korean presidential office

North Korea has again sent balloons believed to be carrying rubbish across the heavily guarded border into South Korea, the Yonhap news agency reported on Wednesday.

At least one of the balloons had landed on the grounds of the South Korean presidential office, Yonhap reported, citing the Presidential Security Service (PSS).

"An investigation by the chemical, biological and radiological response team showed the objects did not present a danger or contamination, so they were retrieved," the PSS said.

Yonhap cited the South Korean Joint Chiefs of Staff (JCS) as saying that a number of balloons floated across the border around Seoul and the surrounding province. The JCS advised people not to touch the objects but to report them to authorities, Yonhap reported.

Since the end of May, North Korea has sent more than 3,000 trash-filled balloons into the South, including some 500 on Sunday, the news agency reported.

North Korea's balloon actions are a reaction to similar activities by South Korean groups, which repeatedly send thousands of leaflets and other propaganda material across the border in huge gas balloons.

Tensions have been on the rise again along the demilitarized zone and the maritime border that separate the two Korean nations, who are still officially at war since a conflict in the 1950s.