North Korean leader Kim Jong Il has been dead for years and replaced by a number of look-alikes, a Japanese academic claims.

One of Kim Jong Il's doubles in 2008 (left) and the real Kim in 2003

North Korea expert Professor Toshimitsu Shigemura, a professor of international relations, says Kim died of diabetes in 2003 and has been substituted by up to four body doubles ever since.

Driven by a fear of assassination, Kim allegedly trained his doppelgangers — one of whom underwent plastic surgery — to attend public appearances.

“Scholars don’t trust my reasoning but intelligence people see the possibility that it will turn out to be accurate,” Fox News reported Professor Shigemura as saying.

“I have identified and pinned down every source.”

Kim, 66, has not appeared in public for three weeks amid rumours he is seriously unwell.

While Seoul intelligence officials have said they believe he has diabetes and heart problems, they do not think he is near death.

But Professor Shigemura, from Tokyo’s respected Waseda University, believes that Kim actually died sometime during a 42-day absence from public in September 2003.

He claims that whenever anyone is granted a face-to-face meeting with today’s Kim, a senior official is always by his side “like a puppet master”.

Professor Shigemura’s claims, outlined in his book The True Character of Kim Jong-il, have been disputed by North Korean officials.