This undated file photo shows a monument in North Korea's North Hwanghae Province that commemorates national founder Kim Il-sung seen from the South Korean border town of Paju. Yonhap

South Korea's military said Tuesday it is vetting objects assumed to be propaganda leaflets distributed by North Korea.

"The military is taking measures after unidentified objects assumed to be North Korean propaganda leaflets were found in border areas in Gyeonggi and Gangwon provinces," the Joint Chiefs of Staff (JCS) said in a notice sent to the press.

The JCS advised residents in the areas to refrain from accessing the objects and report to nearby military or police authorities in the event they discover such objects.

Earlier, North Korea warned of taking "tit-for-tat action" against the distribution of anti-Pyongyang leaflets in border areas.

"Mounds of wastepaper and filth will soon be scattered over the border areas and the interior of the ROK and it will directly experience how much effort is required to remove them," Kim Kang-il, the North's vice defense minister, said in a statement released via state media, using the acronym for South Korea's official name.

For years, North Korean defectors in South Korea and conservative activists have sent balloons carrying leaflets critical of the North's leader Kim Jong-un into North Korea.

Pyongyang has bristled at the propaganda campaign amid concern that an influx of outside information could pose a threat to the Kim regime. (Yonhap)