North Korea on Sunday renewed its threats against a South Korean civic group's plan to send anti-Pyongyang fliers across the border via balloon, warning it will use "all the firepower strike means" to destroy them.

The message, posted as an open notice by the frontline units of the North's Korean People's Army (KPA), came about a week after a leading activist in Seoul reaffirmed his intent to scatter materials criticizing the communist regime across the border around March 26.

The date marks the 5th anniversary of Pyongyang's torpedoing of the South Korean corvette Cheonan.

Park Sang-hak, head of the activist group, said earlier this month he and other North Korean defectors would release balloons holding 500,000 leaflets, as well as DVDs of the U.S. film "The Interview," a comedy depicting a fictitious assassination of the North's leader Kim Jong-un.

According to the North's state-run Korean Central News Agency (KCNA), the KPA's open notice said the campaign "deliberately (escalates) tension on the Korean peninsula where the situation has reached the brink of war" on top of the annual Seoul-Washington military drills that kicked off March 2.

Should the campaign be carried out, the North's frontline army will "blow up" the balloons with "all the firepower strike means,"

it said, adding that any countermeasures will "entail double and treble merciless retaliatory strikes."

In October the two Koreas exchanged gunfire after the North attempted to shoot down balloons carrying similar leaflets. South Korea suffered no casualties or property damage.

South Korea's Joint Chiefs of Staff (JCS) said it will handle any provocation by the North with "powerful and firm" measures.

"A civic group's scattering of leaflets is a part of its rights to free speech, and we clearly state once again that it is those people's judgment call to make and cannot be restricted by force," the JCS said in a release.

The two Koreas are technically still at war after the 1950-1953 Korean War ended in a ceasefire, not a peace treaty.

Nearly 2 million troops, including 28,500 U.S. forces, are on standby across the heavily armed border.

Despite Pyongyang's continued threats pressing the South Korean government to put a stop to the anti-North campaigns, the conservative Park Geun-hye administration here maintains that it does not have the legal means to forbid it, which could be seen as a restriction on freedom of speech.

A recent court ruling, however, dictated that while freedom of speech is a relevant factor, authorities can ban the spread of the fliers if it puts public safety at risk, considering Pyongyang's warnings of military retaliation.

The unification ministry said it respects the court's decision and that it will continue to seek appropriate measures to protect people from any possible outbursts by the North. (Yonhap)