North Korea has launched more than 250 trash-carrying balloons toward South Korea overnight, Seoul's military said Wednesday, marking the sixth launch of such balloons since late last month.

Some 100 balloons, mostly carrying scrap paper, landed in Seoul and the northern part of Gyeonggi Province that surrounds the capital, the Joint Chiefs of Staff said in a notice to reporters.

As of 9 a.m., there were no balloons floating in the air, while an analysis of retrieved balloons showed they did not contain any harmful substances, the JCS said.

North Korea is estimated to have launched more than 2,000 trash-carrying balloons since May 28 in a tit-for-tat move against anti-Pyongyang leaflets sent by North Korean defectors and activists in the South.

In response to the balloon campaign, South Korea blared anti-Pyongyang broadcasts through its border loudspeakers on June 9 for the first time in six years. But the broadcasts have not continued in an apparent bid to prevent the situation from spiraling out of control.

The JCS said it remains ready to conduct loudspeaker broadcasts at any time and warned the implementation of such operations would depend on North Korea's actions.

Early Wednesday, the North also fired a ballistic missile toward the East Sea, but the launch is believed to have failed, according to the JCS. (Yonhap)