South Korea has said KIM JONG UN is "alive and well" following reports the leader had fallen seriously ill after undergoing heart surgery.

MOON CHUNG-IN, the top foreign policy adviser to South Korean President MOON JAE-IN, told newsmen that "the  government position is firm.”

The North Korean leader was last seen in public on 11 April at a meeting of the ruling Workers' Party.

The third-generation hereditary leader, who came to power in 2011 following the death of his father, has no clear successor.