South Korea said Monday it would re-examine the issue of activists floating anti-Pyongyang leaflets into North Korea after an exchange of fire on the border, but stressed it could not simply ban the practice.

North Korea has long condemned the launch of large bundles of leaflets attached to giant helium balloons as a provocation, and last Friday it attempted to shoot some down with large-calibre machine guns.

North Korea warned Monday that the untended remains of U.S. servicemen killed in the Korean War were being "carried away" by giant infrastructure projects and blamed Washington for suspending efforts for their recovery.

Close to 8,000 Americans remain unaccounted for from the 1950-53 Korean conflict, according to the U.S. Defense Department.

North Korea's state media warned Sunday of a rupture in dialogue with rival South Korea over the launch of anti-Pyongyang propaganda leaflets that sparked a brief cross-border exchange of fire.

The two Koreas had agreed a week earlier to work on resuming a formal high-level dialogue that has effectively been suspended for seven months, raising hopes of a thaw in strained relations.

North Korea's state media said Saturday high-level talks with Seoul were now all but scrapped over the launch of anti-Pyongyang propaganda leaflets from the South, which triggered an exchange of fire across the tense border.

The two Koreas had agreed a week earlier to work on resuming a formal high-level dialogue that has effectively been suspended for seven months, raising hopes of a thaw in strained relations.

The two Koreas traded heavy machine-gun fire across their border Friday, as "missing" North Korean leader Kim Jong-Un's failed to attend a key political event, fueling further speculation about his physical health and political future.

No casualties were reported in the exchange of fire which South Korea said was triggered by the North Korean military trying to shoot down balloons carrying anti-Pyongyang leaflets that were launched by activists in the South around 2:00pm (0500 GMT).

North Korean leader Kim Jong-Un missed another key political event Friday, extending a month-long absence and fueling further speculation about his physical health and political future.

However South Korea said it believed Kim was still in full control of the nuclear-armed nation, and the North's state media lauded him as a model of "dignity and invincibility" whose authority was unquestioned.

The European Union and Japan are asking the United Nations to press for war crimes prosecutions in North Korea following a report that laid bare Pyongyang's brutality, according to a draft resolution circulating Thursday.

The measure to be presented to the U.N. General Assembly in the coming weeks would also ask the Security Council to consider targeted sanctions against North Korean leaders "who appear to be most responsible for crimes against humanity."

North Korea warned Thursday of a "catastrophic" end in cross-border relations unless South Korea stops the planned launch of anti-Pyongyang leaflets marking a key political event this week in the communist country.

South Korean activists plan to send anti-Pyongyang leaflets into the North from a site near the border on Friday, when Pyongyang celebrates the anniversary of the founding of its ruling Workers' Party.

North Korean leader Kim Jong-Un, who has not been seen in public for more than a month, is believed to be staying outside Pyongyang, South Korea's defense chief said Tuesday.

"As far as I know, (Kim) is staying at a certain place north of Pyongyang," Defense Minister Han Min-Koo said when lawmakers visited his office for a regular parliamentary inspection of military affairs, without elaborating on Kim's whereabouts.

North and South Korean naval patrol boats briefly exchanged warning fire Tuesday near their disputed Yellow Sea border which has been the site of numerous clashes in the past, the South's defense ministry said.

The incident came as hopes had been raised of a constructive reboot in strained inter-Korean relations following the surprise visit of a top-ranking North Korean delegation to the South just three days before.