North Korea said Wednesday it has rejected South Korea's offer to send special envoys and will redeploy troops to two inter-Korean business zones near the border, unrelentingly ratcheting up tensions a day after the regime blew up a joint liaison office.

The North's disclosure of its rejection of the special envoy proposal shows the regime has no intention to defuse tensions through dialogue and will carry out a series of measures it has threatened to take in anger over propaganda leaflets criticizing its leader.

The sister of North Korean leader Kim Jong-un also issued a harshly worded statement lambasting South Korean President Moon Jae-in for failing to apologize for such leafleting and accusing him of "pro-US flunkeyism."

South Korea reacted angrily to the North's moves, with the presidential office Cheong Wa Dae slamming the North Korean leader's sister, Kim Yo-jong, for her "rude" and "senseless" criticism and warning it will no longer tolerate such "indiscreet" words and acts.

It also denounced the North's disclosure of its special envoy offer as an "unprecedentedly senseless act."

The defense ministry warned that the North will pay the price if it actually takes military action, and the unification ministry expressed "strong regret" over the North's plan to send troops to the joint economic zones.

The exchange of threats and warnings marked a new high in tensions, aggravated dramatically by the North's blowing up of an inter-Korean liaison office building Tuesday, and deepened fears that the situation could spiral out of control into accidental clashes.

Earlier, the General Staff of the North's Korean People's Army said it will send troops to the now-shuttered inter-Korean industrial complex in its border city of Kaesong and the Mount Kumgang tourist zone on the east coast -- two key symbols of inter-Korean reconciliation.

The North also said it will restore guard posts removed from the Demilitarized Zone separating the two sides and resume "all kinds of regular military exercises" near the inter-Korean border in an apparent move to abolish a military tension-reduction deal signed in 2018.

"Units of the regiment level and necessary firepower sub-units with defense mission will be deployed in the Mount Kumgang tourist area and the Kaesong Industrial Zone," a spokesperson of the General Staff said in a statement carried by the Korean Central News Agency.   

"Civil police posts that had been withdrawn from the Demilitarized Zone under the north-south agreement in the military field will be set up again to strengthen the guard over the front line," it said.

North Korea has taken a series of retaliatory action against South Korea, denouncing the sending of leaflets criticizing its leadership and regime by defectors and other activists as an act that breaches inter-Korean agreements.

Pyongyang has vowed to deal with South Korea as an "enemy" and cut off all cross-border communication lines, and threatened to take other measures, including military action. It has also threatened to dismantle a now-shuttered joint industrial park in Kaesong and scrap the 2018 military deal the two Koreas signed to reduce cross-border tensions.

In a surprise move, North Korea blew up the inter-Korean joint liaison office.

In response, South Korea expressed "strong regret" and warned of a "strong response" if the North takes measures further aggravating the situation.

Up until then, the South appeared to be trying to exercise restraint, but what prompted it to erupt in anger was the blistering statement that the North Korean leader's sister issued to blast President Moon and his speech delivered Monday to mark the 20th anniversary of the first-ever inter-Korean summit in 2000.

She called the speech "sickening," "brazen-faced" and full of self-defense and deep-rooted toadyism intended to avoid responsibility without making an apology over the leafleting issue. She also called Moon "an impudent man" with "disgusting behavior," accusing him of being subservient to the United States.

"The recent speeches made by the South Korean chief executive should have reflected his apology, repentance and firm pledge to prevent the recurrence of similar occurrences. But his speech was full of excuses and spurious rhetoric to get rid of responsibility, without any mention of the means and the end," she said.

"It is truly sophism full of shamelessness and impudence," she added. "Now they are trying to shift the responsibility for the results of their own making on to us. This is literally a brazen-faced and preposterous act."

Moon's office strongly bristled at the statement.

"It is a senseless act to disparage (Moon's speech earlier this week) in a very rude tone without understanding its purpose at all," Yoon Do-han, Cheong Wa Dae's senior secretary for public communication, said.

"We won't tolerate any more of North Korea's indiscreet rhetoric and acts, which fundamentally harm the mutual trust the leaders of the two sides have built so far," he said. "We hope the North side will have basic courtesy."

Relations between the two Koreas have almost stalled since a second summit between the North's leader and US President Donald Trump ended without an agreement in February last year due to differences over how to exchange sanctions relief and denuclearization measures.

In Washington, the State Department urged the North to refrain from "further counterproductive actions."

"The United States fully supports the ROK's efforts on inter-Korean relations and urges the DPRK to refrain from further counterproductive actions," a State Department spokesperson told Yonhap News Agency, using the acronyms for the official names of South Korea, the Republic of Korea, and North Korea, the Democratic People's Republic of Korea.

"We are aware that North Korea destroyed the liaison office in Kaesong and remain in close coordination with our Republic of Korea allies," a senior US government official told Yonhap earlier. (Yonhap)