In a "stern warning" to Seoul, North Korea Tuesday said South should be "ready for paying a gruesome and dear price" over sending propaganda leaflets and balloons, state media reported.
"If the ROK scum persist in their crude and dirty play, the mode of counteraction of the DPRK will inevitably be changed," said Kim Yo Jong, sister of North Korean leader Kim Jong Un.
ROK, or Republic of Korea, is the official name of South Korea while Pyongyang is referred to as Democratic People's Republic of Korea or DPRK.
Kim, who is vice department director of the Central Committee of the Workers' Party of Korea, said Pyongyang early Tuesday detected 29 large balloons sent by Seoul "on the southern border and in some deep areas" of North Korea.
She said 10 large balloons were found in Cholwon county, eight in Sinphyong county, five in Ichon county, four in Phangyo county, one in Koksan county and one in Phyonggang county, adding that: "Specialized organs are now searching, disposing of and incinerating them."
Kim said leaflets were also found in various areas of North Korea.
"The specialized organs are busy with their work and people's inconvenience is increasing in many areas due to the blocking of relevant districts," said Kim. "It seems that the situation we cannot overlook is coming."
Earlier, Seoul had said North Korea flew hundreds of balloons, carrying trash, into the South Korean territory.
