SEOUL, Dec 19, 2011 (AFP) - The young man tipped to be North Korea's next leader and propel the Kim dynasty into a third generation is even more of an enigma than his mercurial father Kim Jong-Il, who has died at the age of 69.North Korean state media on Monday urged people to follow Kim's youngest son and heir apparent Kim Jong-Un, aged in his late 20s, after announcing that his father had died on Saturday, plunging the country into confusion.

Kim Jong-Un's life is shrouded in mystery, but in recent years he has been pushed to the forefront as his father apparently speeded up plans for a second dynastic succession after suffering a stroke in August 2008.

In September 2010 the son was made a four-star general and given senior ruling party posts, despite his lack of any military experience. It was only then that state media published his first-ever adult photograph.

Since his elevation, Kim Jong-Un has been constantly at his father's side, and said to be actively involved in state affairs.

North Korea's propaganda machine has rolled into action to build up the same personality cult for Jong-Un that surrounded his father and late grandfather Kim Il-Sung, the founder and "eternal leader" of North Korea who died in 1994.

In recent months, state media began referring to him as "general", after having previously only used his official title -- vice-chairman of the central military commission of the Workers' Party of Korea.

"The latest move indicates Kim Jong-Un is being put forward formally as a powerful leader like his father," Sejong Institute analyst Cheong Seong-Chang, a specialist in the succession issue, said in October.

"Such a title has been used internally but North Korea now appears to be boosting the image of Jong-Un as military leader," he added.

Little is known about the succession. South Korea's top official on cross-border affairs said last month that there would be challenges in transferring power to the son.

Kim Jong-Il's only sister Kim Kyong-Hui and her husband Jang Song-Thaek, the country's unofficial number-two leader, are expected to act as his guardian and throw their political weight behind him, analysts say.

In a memoir, Kenji Fujimoto, a former Japanese sushi chef for Kim Jong-Il, described the Swiss-educated Jong-Un as a "chip off the old block, a spitting image of his father in terms of face, body shape and personality"

Despite the dearth of information, Jong-Un has made headlines since his name was floated by South Korean media in early 2009 as the figure being groomed to succeed his father.

Little is known for sure about his character but experts believe he has traits in common with his father.

"Jong-Un is known to have the potential to become a strong, ruthless leader. He has a take-charge personality," Sejong Institute's Cheong has told AFP.

"As a result, as of the summer of 2010, Kim Jong-Un peddles influence, excluding in foreign affairs matters, on state affairs on a level similar to that of Kim Jong-Il."

South Korea's spy chief Won Sei-Hoon said last year that Kim Jong-Il's poor health had driven him to speed up preparations for the transfer of power, with the son taking a bigger role in policy-making and frequently accompanying his father on trips.

Some analysts had seen second son Kim Jong-Chul as favourite to take over.

But Fujimoto said in his memoir that Kim thought of Jong-Chul as too feminine and unfit for leadership.

Eldest son Jong-Nam apparently spoiled his prospects after being deported from Japan in 2001 for trying to enter with a forged passport while attempting a visit to Tokyo Disneyland.

Jong-Un was born to the leader's third wife, Japan-born ethnic Korean dancer Ko Yong-Hi, who is believed to have died of breast cancer in 2004.

He is believed to have studied at international school in Switzerland under a false name.

Newspaper reports say he enjoyed basketball and drawing cartoons in Switzerland, where school staff and friends reportedly remembered a shy boy who liked skiing and Hollywood tough guy Jean-Claude Van Damme.

Back in Pyongyang, South Korea's Yonhap news agency has reported, he attended the Kim Il-Sung Military University and graduated in 2007.