North Korea's Kim oversees transfer of missile launchers to border

North Korean leader Kim Jong Un oversaw the delivery of 250 ballistic missile launchers to frontline units along the southern border, calling the weapons a "powerful treasured sword" to defend sovereignty, state media said Monday.

The "ceremony for transferring 250 new-type tactical ballistic missile launchers... to the frontier military units" took place in capital Pyongyang on Sunday, the official Korean Central News Agency reported, with Kim presiding over the event.

The missile launchers were an "up-to-date tactical attack weapon", Kim was quoted as saying in a speech, adding he "personally designed" them himself.

Relations between the two Koreas are at one of their lowest points in years, with the North ramping up weapons testing and bombarding the South with balloons full of trash.

South Korea has responded by resuming propaganda broadcasts along the border, suspending a tension-reducing military deal and restarting live-fire drills near the border.

This year, Pyongyang declared South Korea its "principal enemy", jettisoned agencies dedicated to reunification and outreach, and threatened war over "even 0.001 mm" of territorial infringement.

Kim said in his speech that presenting the new weapons at a time when the country was reeling from flood damage was a "manifestation of the firm will of our Party to push ahead with the bolstering of defence capabilities", according to KCNA.

Heavy rainfall hit the nuclear-armed country's northern regions in late July, with a South Korean media report claiming up to 1,500 people could have died.

Kim has lashed out at the reports, dismissing them as a "smear campaign to bring disgrace upon us and tarnish" the North's image.

The North has said there were no casualties at all in the Sinuiju area, the region Pyongyang said had suffered the "greatest flood damage".

It claimed North Korea's Air Force rescued over 5,000 people, with around 4,200 of them saved by helicopter "within a few hours".