The unification ministry warned Friday that "unendurably" painful measures would be taken against North Korea if it continues to stage "irrational" provocative acts, such as this week's sending of balloons carrying trash to South Korea.

Earlier this week, North Korea flew hundreds of large balloons carrying trash and manure into South Korea and staged GPS jamming attacks in waters near South Korea's northwestern border islands for a third straight day until Friday. The country also fired a salvo of short-range ballistic missiles toward the East Sea on Thursday.

The ministry in charge of inter-Korean affairs voiced "strong" regret over North Korea's "senseless and irrational" provocative acts.

"The government is taking the North's latest provocations very seriously. We will not tolerate such moves," the ministry said.

"If North Korea does not stop its provocative acts, the government will take all measures that North Korea cannot endure. We sternly warn that all responsibility for what will take place afterwards will totally rest on North Korea," it noted.

The message came as North Korea is widely expected to further conduct provocative acts amid its outright animosity toward the South.

Kim Yo-jong, the powerful sister of the North's leader Kim Jong-un, issued a statement laden with mockery Wednesday night, saying that the balloons were "sincere presents" for South Koreans who are crying for the guarantee for freedom of expression. She said her country will send rubbish "dozens of times" more than those being scattered in the North.

A Seoul military official said the North may send more of such balloons Saturday when the wind is forecast to blow in a southward direction.

Kim Jong-un also supervised a firing drill involving super-large multiple rocket launchers Thursday. The North's state media said the drill was aimed at demonstrating the country's resolve to stage a preemptive strike against South Korea, if provoked.

At a year-end party meeting, Kim defined inter-Korean ties as those "between two states hostile to each other" and said there is no point in seeking reconciliation and unification with South Korea. (Yonhap)