The powerful sister of the North Korean leader Kim Jong UnKim Yo Jong, today threatened South Korea with “terrible destruction” if drones loaded with propaganda leaflets cross the border again.

“In the event that a Republic of Korea (South Korea) drone is detected in the skies above our capital again, it will definitely lead to a terrible disaster,” warned Kim Yo-yong, a key spokeswoman for the North Korean authorities.

Yesterday Friday Pyongyang accused Seoul of sending drones carrying propaganda leaflets into North Korean airspace on October 3 and again on Wednesday and Thursday.

The drones dropped propaganda leaflets hostile to the Pyongyang regime, which contained “abhorrent slander”, according to the North’s KCNA news agency.

South Korean Defense Minister Kim Jong-hyun initially denied Pyongyang’s accusations, but the chief of the military’s general staff pushed back on Seoul’s position, saying he “cannot confirm whether North Korea’s claims are true or not.”

Her denial Seoul to confirm means the drones were sent by “military gangsters,” Kim Yo-yong said today.

Her Foreign Ministry North Korea issued an “ultimatum” to South Korea to stop these “impermissible provocations”, as he called them.

Photos purported to be from propaganda leaflets were shared by North Korean official media, along with a blurry photo of an “unmanned drone”.

Despite efforts by authorities to prevent them, South Korean activists have for years flown balloons containing propaganda and US dollars into North Korea, actions that have angered Pyongyang.

Pyongyang has launched nearly 5,000 garbage-filled balloons into South Korea since May in what it calls retaliation for propaganda balloons launched by South Koreans.

According to the South Korean news agency Yonhap, Pyongyang launched balloons filled with waste again last Friday night

Relations between the two neighbors are at their lowest point in years, with North Korean leader Kim Jong Un this year naming South Korea as his country’s “main enemy”.