South Korea will begin loudspeaker broadcasts directed at North Korea on Sunday that will be "unbearable" for the Kim Jong Un regime, its National Security Council said, after Pyongyang resumed sending balloons carrying trash across the border.

The Council met on Sunday morning, after dozens of balloons with trash attached were found in Seoul and in areas near the border earlier in the day and overnight.

"The measures we will take may be unbearable for the North Korean regime but they will send a message of hope and light to the North's troops and its people," the Council said.