North Korea has started dropping used toilet paper onto South Korean soil in response to its arch rival blasting pop songs and propaganda over the border.

The Communist state began sending balloons stuffed with human waste, cigarette butts and propaganda leaflets on January 12, The Joongang Daily reports.

South Korea recently restarted broadcasting K-pop songs over the border. (Getty)

"When we opened up a bundle dropped on the ground, we found plastic bags filled with leaflets mixed with trash," a South Korean military official said.

"There was concern that North Korea may have sent biochemical substances to harm our people, but after analysing the content, it was just trash.

"Between the leaflets, there was lots of filth difficult to describe in words."

The unwelcome content is in response to the South Korean military blasting up tempo K-pop songs over the border, which in turn was initiated as a response to Pyongyang's claimed hydrogen bomb test on January 6.

A number of balloons have failed to explode over South Korean soil, allowing officials to properly analyse their contents.

North Korean guards in the Joint Security Area of the Korean Demilitarized Zone (Getty) (Getty)

One leaflet brands South Korean President Park Geun-hye "political filth".

"In South Korea, we maintain a level of dignity toward the top leader of a country," a government official said.