North Korea has officially confirmed the purging of its defence chief two months after Seoul's spy service said he had been executed with an anti-aircraft gun for disloyalty to leader Kim Jong Un.

South Korea's National Intelligence Service told MPs in May that people's armed forces minister Hyon Yong Chol was killed on a firing range in front of a crowd for talking back to Kim, complaining about his policies and sleeping during a meeting.

The North's state media has since not mentioned Mr Hyon or his disappearance. But over the weekend, the country's official Korean Central News Agency named army general Pak Yong Sik as the armed forces minister in a dispatch about a meeting with a Lao military delegation.

South Korean Unification Ministry spokesman Jeong Joon-Hee said this confirmed Mr Hyon's replacement and purging.

Since taking power upon the death of his dictator father Kim Jong Il in December 2011, Kim has orchestrated a series of executions, purgings and personnel reshuffles in what outside analysts say is an attempt to bolster his grip on power.