The sister of North Korean leader Kim Jong-un slammed South Korea for failing to stop anti-Pyongyang leaflets flown by a defector group last week, calling it an "intolerable provocation" and warning of "corresponding action."

Kim Yo-jong made the remarks in a statement carried by the official Korean Central News Agency, saying that the South Korean government "again did not stop the reckless acts" and expressed "displeasure" over the matter.

"'Defectors from the North' in South Korea recently scattered leaflets against the DPRK again, an intolerable provocation against it," Kim said in the statement. "However, the South Korean authorities again did not stop the reckless acts of the 'defectors from the North,' winking at them."

DPRK is the acronym of the North's official name, the Democratic People's Republic of Korea.

"Displeasure cannot be hidden over such sordid acts... We regard the maneuvers committed by the human wastes in the South as a serious provocation against our state and will look into corresponding action," she said. "We can no longer remain an onlooker."

She, however, did not elaborate on what the action could be.

On Friday, Fighters for a Free North Korea led by Park Sang-hak, a vocal North Korean defector, claimed that it had flown 10 large balloons carrying around 500,000 leaflets along with 500 booklets and 5,000 $1 bills from unidentified border areas into the North.

This marked the first of its kind since the Seoul government's ban on leafleting went into effect in late March.

The ban came months after the North blew up an inter-Korean liaison office in the border town of Kaesong, a symbol of a thaw in inter-Korean relations, in anger over Seoul's failure to stop such leafleting.

Critics have claimed the legislation is tantamount to caving to the North's pressure.

The South Korean government has said that the prohibition is necessary to protect the lives and safety of residents living in the border areas as such leaflets often mocking the North's leaders and regime could provoke Pyongyang.

Hours after the statement, Seoul's unification ministry handling cross-border issues urged all, including the North, to refrain from actions that could heighten tensions surrounding the Korean Peninsula, vowing its continued efforts to build peace and move inter-Korean relations forward.

The ministry also reiterated that it is now conducting an investigation with relevant authorities into last week's claimed sending of leaflets, while saying that the anti-leafleting ban should be observed in accordance with its purpose of protecting the safety and lives of its citizens in border areas. (Yonhap)