The powerful sister of North Korean leader Kim Jong-un said Sunday that South Korea should be ready to pay "a very high price" for sending anti-Pyongyang leaflets north of the border, calling such an act "dirty play."Kim Yo-jong, vice department director at the ruling Workers' Party, said she was informed earlier in the day by party and military officials that "dirty leaflets and things" had been discovered in 17 places in the border region and other areas of her country. Kim said those leaflets were burned, according to the regulation on handling "enemy-dropped objects.""Despite the repeated warnings of the DPRK, the ROK scum are not stopping this crude and dirty play," Kim said in an English-language statement carried by the North's official Korean Central News Agency (KCNA). DPRK is short for the North's official name, Democratic People's Republic of Korea. ROK refers to the South's official name, Republic of Korea."As already warned, the scum, who are resorting to do this play, will be more strongl y criticized by their people. We have fully introduced our countermeasure in such situation," Kim continued. "The ROK clans will be tired from suffering a bitter embarrassment, and must be ready for paying a very high price for their dirty play."So far this year, North Korea has responded to leaflets from South Korea by sending balloons filled with trash across the border. South Korea then pushed back by blaring anti-Pyongyang broadcasts through its border loudspeakers.In an unprecedented move, the KCNA released a photo showing leaflets flown in from South Korea being burned, along with a pack of cold medicine.Source: Yonhap News Agency