Pyongyang this month began a crackdown on senior officials suspected of corruption, starting in Musan county in the northeastern province of North Hamkyong, said the Seoul-based North Korea Intellectuals Solidarity.
A spokesman said the information came from North Korean sources whom he described as senior party officials closely connected with the investigation.
"About 15 heavyweight officials, many of them military, are being investigated for turning a blind eye to people fleeing the country and being involved in smuggling activities," the spokesman told AFP.
He said the investigation was being led by Kim Jong-Un, youngest son and chosen successor to leader Kim Jong-Il.
The crackdown, which would be expanded into a nationwide campaign, was a "politically-motivated purge" aimed at replacing longstanding military members with younger officials more loyal to Jong-Un, said the spokesman.
"This is a purge for generational change... senior officials are trembling with fear because they don't know where heads are going to roll," he said.
Seoul's intelligence agency declined to comment on the report.
The Kim dynasty, which has ruled the communist country with an iron fist for more than six decades, has long used purges to maintain its grip on power.
Founding president Kim Il-Sung reportedly executed hundreds of dissidents during the early years of his leadership and often persecuted senior officials showing signs of rebelliousness.
Kim Jong-Il, after taking over from his father, is known to have executed several hundred soldiers for showing "suspicious movements", Wednesday's Chosun Ilbo newspaper reported.
Jong-Un, believed to be aged 27, was made a general and given powerful party posts at the country's largest political gathering for 30 years in September.
Sixty-eight-year-old Kim Jong-Il is believed to be accelerating preparations for another hereditary power transfer due to worsening health after he suffered a stroke in 2008.
Source: channel news asia