North Korea has sent around 720 more balloons carrying trash to South Korea and continued jamming GPS signals for five straight days against the South, Seoul's military said Sunday, as South Korea's presidential office was considering taking countermeasures.

South Korea's Joint Chiefs of Staff said it has detected some 720 balloons that floated across the Military Demarcation Line separating the two Koreas and fell in different parts of the country between 8 p.m. Saturday and 1 p.m. Sunday.

The balloons carried various pieces of trash, such as cigarette butts, paper and plastic bags, just like the previous balloons, according to the JCS.

"About 20 to 50 balloons are moving per hour through the air and coming down in Seoul, Gyeonggi Province, North Chungcheong Province and North Gyeongsang Province," a JCS official said on the condition of anonymity.

The official later stated that no additional balloons had been detected after 1 p.m.

North Korea previously sent around 260 balloons carrying trash and excrement to the South on Tuesday and Wednesday after it warned of a "tit-for-tat action" against anti-Pyongyang leaflets sent by the South's activists.

The total number of balloons is similar to the total amount observed annually in the 2016-2017 period.

The JCS advised people not to touch the objects and report them to nearby military or police authorities. It also warned of possible danger from the balloons.

The military dispatched teams to recover the debris instead of shooting down the balloons, as the possibility of them carrying toxic chemicals cannot be completely ruled out.

There have been no reports of injuries so far.

The Seoul city government also said Sunday that it will operate an emergency center 24 hours a day to respond to such objects.

North Korea has been jamming GPS signals near the border since Wednesday.

The North's balloon launches come after a recent series of provocative steps, including the botched attempt to launch a spy satellite Monday. The country staged GPS jamming attacks in waters near South Korea's northwestern border islands for the fourth straight day Saturday.

North Korea also fired a barrage of artillery from super-large multiple rocket launchers toward the East Sea on Thursday in a drill that it said was to demonstrate its resolve to conduct a preemptive strike against South Korea.

South Korea's presidential office is set to hold a meeting of the National Security Council later Sunday to discuss the North's balloon provocation.

Seoul's unification ministry warned Friday it will take "unendurably" painful measures against North Korea if it continues to stage "irrational" provocative acts.

South Korea may consider staging psychological warfare against North Korea, including military authorities' resumption of loudspeaker broadcasting along the border or the sending of leaflets critical of the North's regime.

On Sunday, the defense chiefs of South Korea and the United States denounced North Korea over its latest provocations, including the launches of trash-carrying balloons and a military spy satellite.

South Korean Defense Minister Shin Won-sik and his US counterpart, Lloyd Austin, made the criticism as they met on the sidelines of the Shangri-La Dialogue. (Yonhap)