The sources say Pak Nam-gi was executed by a firing squad in Pyongyang last week for intentionally ruining the national economy, The Korea Herald reported Thursday.
Pak is being blamed for last year's failed currency reform and growing public unrest over North Korea's faltering economy, one unnamed source is quoted as saying.
The North is reportedly describing Pak as "a landlord's son who snuck into the revolutionary ranks to intentionally wreck the economy."
the South Korean Unification Ministry says it is unable to officially confirm reports of Pak's execution.
Pak had served as Kim Jong-il's key economic aide.