Kim Jong-un, the North Korean leader, ordered the public execution of one of his most senior ministry officials and the banishment of two more bureacrats for re-education, according to South Korea's Unification Ministry.

South Korean media reports have claimed that Kim Yong-jin, a vice premier in the North Korean cabinet with responsibilty for education affairs, was executed alongside another ministry official with an anti-aircraft gun in July.

The killings are the start of a "new reign of terror" in the aftermath of a series of recent high-profile defections, the reports suggested.

Sources told South Korea's JoongAng Ilbo newspaper that Kim Yong-jin made the mistake of falling asleep in a meeting with Mr Kim.