The leaflets attacking South Korean President Yoon Suk Yeol and First Lady Kim Keon Hee found in the capital appear to be the first instance of the North Korean government directly sending anti-South propaganda material across the border.
They included graphic messages accusing the Yoon government of failures that had left his people living in despair, and describing the first couple as immoral and mentally unstable.
The resumption of a campaign by Pyongyang to send balloons into its neighbour comes as tensions on the peninsula have spiked with the North accusing South Korea's military of sending drones over Pyongyang to violate its sovereignty.
Since late May, North Korea has been sending thousands of balloons often carrying trash into various parts of South Korea saying it was to retaliate for propaganda leaflets sent the other way by South Korean activists criticising the North's leadership, with Pyongyang accusing Seoul of being complicit.
South Korea's military said early on Thursday that North Korea had again sent balloons carrying suspected trash and they were headed to the capital region and the eastern part of South Korea.
The Presidential Security Service said in a statement trash dropped from North Korean balloons was found around the presidential office but it posed no security or contamination risk. It did not provide further details of the material.
The North Korean balloons have caused some property damage as they landed in the South including starting small fires from the trigger that releases the trash but otherwise were retrieved by authorities without incident.
The South Korean government has declined to say if drones were flown toward the North or who may have sent them.
