Safety personnel inspect and clean debris from a trash-carrying balloon near Jeongdong Theater in Jung District, Seoul, July 24. Yonhap

North Korea again launched trash-carrying balloons toward South Korea on Wednesday, the Joint Chiefs of Staff (JCS) said, with some pieces of garbage landing on the presidential office compound in Seoul.

The launch, which marked the second of its kind this week, came as the South Korean military blared anti-Pyongyang broadcasts in full-scale through its border loudspeakers for the fourth day in response to the North's continued launches.

Earlier in the day, the Presidential Security Service discovered fallen trash on the grounds of the complex in central Seoul, as North Korea sent more balloons carrying pieces of scrap paper and other trash.

An analysis of the fallen objects showed they did not present a danger. But the military has refrained from shooting down the balloons out of concern their contents could spread further and cause more damage.

North Korea has launched more than 3,000 trash-carrying balloons since late May, including some 500 such balloons Sunday, in a tit-for-tat move against anti-Pyongyang leaflets sent by North Korean defectors and activists in the South.

Balloons presumably sent by North Korea are seen floating in the sky in Yongsan District, Seoul, July 24. Yonhap

In response, South Korea has resumed full-scale propaganda loudspeaker broadcasts toward the North.

Since Sunday, the military has been conducting daily loudspeaker broadcasts on all the fronts across the roughly 250 kilometer-long inter-Korean border.

The military briefly conducted the broadcasts on June 9 for the first time in six years before turning them off in an apparent bid to prevent the situation from spiraling out of control.

It partly restarted daily loudspeaker operations last week in response to Pyongyang's balloon campaign.

Meanwhile, North Korea began broadcasting crackling sounds through its border loudspeakers on Saturday, according to the military official.

The military suspects the noise could be intended to prevent North Koreans in the border area from listening to the South's broadcasts, the official said, adding that it is likely to have a limited effect.

"From the North's side, our loudspeaker broadcasts and their speaker noise will likely be heard together," the official said.

North Korea has bristled against the loudspeaker campaign, as well as anti-Pyongyang leaflets sent by South Korean activists, on fears that an influx of outside information could pose a threat to the Kim Jong-un regime.

Last week, Kim Yo-jong, the powerful sister of the North's leader, warned of "gruesome and dear" consequences over continued leaflet campaigns.

In 2014, the two Koreas exchanged machine gun fire across the border after the North apparently tried to shoot down balloons carrying propaganda leaflets critical of North Korea. (Yonhap)