North Korea has executed its defence minister by anti-aircraft fire for crimes including falling asleep at a meeting in front of supreme leader Kim Jong Un, Seoul’s intelligence agency has claimed.

Hyon Yong Chol had enjoyed a rapid rise to prominence under Mr Kim: relatively unknown when he was promoted to vice-marshal in 2012, he became one of Pyongyang's most senior officials last year with a ministerial position and a seat on the National Defence Commission, the country’s most powerful organ. His name regularly appeared near the top of the list of officials accompanying Mr Kim to public events.

But Mr Hyon was executed using an anti-aircraft gun in front of hundreds of people near the end of last month, South Korea’s National Intelligence Service told lawmakers in a briefing on Wednesday. This appears to be the latest in an increasingly heavy stream of executions, widely interpreted as part of efforts by the young leader to protect his authority over the state since taking power on his father’s death in December 2011.