Balloons carrying rubbish sent from North Korea since late May have been discovered at more than 3,000 sites throughout South Korea, a police report showed Tuesday.

According to a police report obtained by Democratic Party of Korea Rep. Yang Bu-nam, balloons sent by North Korea were found at 3,359 locations across South Korea between May 28 and July 25, during which 10 balloon campaigns were conducted.

South and North Korea have used balloons in their propaganda campaigns since the Korean War in the 1950s. In late May, North Korea intensified its balloon launches in response to South Korean civic groups sending balloons with leaflets criticizing leader Kim Jong-un. North Korea had warned of a "tit-for-tat action" to counter the leaflets, resulting in the launch of balloons carrying trash and excrement to the South.

The affected locations include areas where balloons and the scraps of waste paper and plastic they carried were scattered upon landing. However, the materials have so far been found to pose no contamination or safety risk.

Balloons sent on the 10th campaign on July 24 had the biggest impact, as they were found to have landed at 1,403 different locations countrywide, according to the report. Balloons and trash were found at 78 locations during the first campaign from May 28-29, while 440 locations were affected by the ninth campaign from July 21-22.

Seoul, Incheon, Gyeonggi Province and Gangwon Province -- all located along or near the inter-Korean border -- were affected in all 10 campaigns, with the capital city experiencing balloons and trash landing at 2,069 locations. Out of Seoul’s 25 districts, Nowon-gu had the greatest number of trash-laden balloon incidents, with 434 reported sites.

In the first balloon campaign, balloons landed as far as the county of Geochang, South Gyeongsang Province, around 300 kilometers from the border. In the 10th balloon campaign on July 24, some North Korean balloons landed near the heavily guarded presidential office in Yongsan-gu, central Seoul.

Furthermore, they have caused significant disruptions at Incheon Airport, the country’s main gateway, on 12 occasions. According to data from the Seoul Regional Aviation Administration submitted to Yang, the airport's runways have closed for a total of 265 minutes due to the balloons.

The first disruption occurred from 10:48 p.m. to 11:42 p.m. on June 1, just four days after the balloon launches began. The most severe incident was on June 26, when airport runways shut down eight times, resulting in 166 minutes of halted takeoffs and landings.

Yang urged the government to quickly implement measures to prevent South Korean activists from conducting leafleting campaigns toward the North, citing North Korea's claims that such activities provoked its balloon campaigns.

The two Koreas remain technically at war since the 1950-53 Korean War ended with an armistice, not a peace treaty.