North Korea Kim Jong-un
North Korea's leader Kim Jong-un visits the Kumsusan Palace of the Sun to mark the 61st anniversary of the end of the Korean War in 1953. Reuters

North Korea's leader Kim Jong-un will be an even more brutal dictator than his father Kim Jong-il, a former family bodyguard has warned.

Lee Young-guk, who defected to South Korea, said Kim Jong-un, who became the North Korea's Supreme Leader in December 2011, has created false loyalty from the populace "based on fear".

"Kim Jong-un ended up killing his uncle [General Jang Song-Thaek], who even Kim Jong-il could not kill," Young-guk said in an interview with CNN.

"As power was handed down to the third generation, it became crueller. Kim Jong-un has created loyalty, but it is fake and based on fear."

Lee served as Kim Jong-il's bodyguard for 10 years, before giving up the role just before Kim Jong-il took power in 1994 when Kim Il-sung died.

The former bodyguard said the North Korean regime ruled by imposing a climate of terror, where people could be executed for minor transgressions.

Speaking of his time with Kim Jong-il, Lee recalled how the dictator imposed death sentences on those who incurred his wrath. One senior official was sent to die at a concentration camp because he used Kim Jong-il's private elevator and ashtray.

"When Kim Jong-il would arrive in his vehicle, 60 to 70-year-old advisers would run away and throw themselves onto the grass," he said.

"They had dust on their clothes, but they wanted to hide from him. They are scared because even when he was happy he would be rude and could chop off their heads."

Lee also described the intense mental and physical training he had to endure in preparation for protecting the former leader, including learning taekwondo and being able to headbutt concrete.

He also described how he was ideologically brainwashed and trained to believe that Kim Jong-il was a god, and that the only reason he was born was to serve and protect the so-called "Dear Leader".

The former bodyguard finally became disillusioned with the regime after seeing the opulent wealth enjoyed by the political elite, contrasted with the stark poverty suffered by the general population.

Lee made his first escape attempt in 1994. However, he was caught and sent to the Yodok political camp.

Lee was eventually escaped, joining an estimated 25,000 defectors in South Korea. He found a job as a duck farmer before becoming a media pundit.