The mystery blast in North Korea was not a nuclear explosion, a western envoy said today after he visited the site.

Britain’s ambassador to North Korea plans to travel tomorrow to the site of an explosion that shot a mushroom cloud into the sky to verify claims it was caused by planned blasting for a hydroelectric project.

NORTH Korea said yesterday that the large explosion near its border with China several days ago was a “deliberate detonation of a mountain” as part of a hydroelectric project.

The British Ambassador to North Korea today described how two schools bore the brunt of a massive train explosion which killed 154 people close to the Chinese border.

SECRETIVE North Korea finally admitted last night that several hundred people were killed and thousands injured when trains carrying explosives and blew up in a station.