SEOUL (AFP) - North Korea said on Monday (June 22) it has readied thousands of balloons and millions of leaflets in preparation for "retaliatory punishment" against South Korea.

The detail, in a state media report, came a day after the North said it was preparing to begin an anti-South leaflet campaign following a series of vitriolic condemnations of Seoul because of anti-North leaflets floated over the border.

Defectors in the South send such leaflets, which criticise the North's leader Kim Jong Un over human rights abuses and his nuclear ambitions. The messages are usually attached to balloons or floated in bottles.

Analysts have said North Korea has been conducting a series of staged provocations aimed at forcing concessions from Seoul and Washington.

"The preparations for the largest-ever distribution of leaflets against the enemy are almost complete," a report by the Korean Central News Agency (KCNA) said.

"Publishing and printing institutions at all levels in the capital city have turned out 12 million leaflets of all kinds reflective of the wrath and hatred of the people from all walks of life," it said.

More than "3,000 balloons of various types capable of scattering leaflets deep inside south Korea, have been prepared," KCNA added.

Inter-Korean relations have been frozen for months, following the collapse of a summit in Hanoi between Kim and US President Donald Trump early last year.

That meeting foundered on what the North would be willing to give up in exchange for a loosening of sanctions.

The nuclear-armed and impoverished North is subject to multiple UN Security Council sanctions over its banned weapons programmes.