South Korea's military said it was on alert for more trash-carrying balloons possibly arriving from North Korea on Sunday, Agence France Presse reported.
In two waves last week, North Korea sent hundreds of balloons with bags of trash into the South, describing them as a response to anti-Pyongyang propaganda balloons sent the other way by South Korean activists.
Pyongyang announced a halt to the balloons on Sunday but days later, a South Korean group called "Fighters for Free North Korea" said it had sent 10 balloons with K-pop music and 200,000 leaflets against leader Kim Jong Un.
The South Korean military is "closely monitoring with vigilance" because of "the possibility of more trash balloons descending around tomorrow", its spokesperson told AFP on Saturday.
North Korea had said it would respond with "wastepaper and rubbish" a hundred times the amount if more South Korean leaflets were sent.
The North Korean balloons last week landed in a number of locations in the South, and were found to be carrying garbage such as cigarette butts, cardboard scrap and waste batteries.
In response to the balloons, South Korea on Tuesday completely suspended a 2018 military deal with the North, which was meant to reduce tensions between the neighbors.
Authorities in Seoul have condemned the North Korean balloons as a "low-class" act and threatened countermeasures that it said Pyongyang would find "unendurable".