But Roy Calley, a journalist who has travelled extensively in the , says such are the levels of secrecy there that not even those living in  will realise what is going on. Mr Calley was speaking after Chang Song-min, a former aide to South Korea’s late President Kim Dae-jung, said he believed the 36-year-old, who has been in power since 2011, was in a .

His claim is the latest with respect to Kim’s health, with widespread rumours of his death surfacing in April when he was not seen in public for a fortnight.

Since then footage has emerged purportedly showing him attending official engagements.

However, Mr Calley, who chronicles his time spent in North Korea during the course of his book, Look With Your Eyes and Tell the World, has always been sceptical, pointing out it was impossible to say with any degree of certainty when they were filmed.
Kim Jong-un Kim Yo-jong
Kim Jong-un is dead, believes Roy Calley – with his sister Kim Yo-jong poised to take over (Image: GETTY)
Kim Jong-un
Kim Jong-un chairs a meeting of officials – but Roy Calley is doubtful about when the pictures were taken (Image: GETTY)

He told Express.co.uk: “I honestly believe he’s dead but you just can’t tell with that country.

“I could be in Pyongyang now and be none the wiser.”

North Korea’s vague statements on Kim Jong-un point towards some major changes being made to operations, Mr Calley said.

With reference to persistent reports speculating about Kim’s health, coupled with suggestions his 32-year-old sister was now regarded as his de-facto successor, Mr Calley said: “The fact that there is so much information /misinformation being released suggests there is something happening.

Kim Yo-jong
Kim Yo-jong, watched on a big screen in South Korea, is seen as increasingly influential (Image: GETTY)

“With everything else the government is very specific with their statements but never when it comes to the leaders.”

He explained: “It was months before the population heard officially that the Dear Leader [Kim Jong-il, Kim’s father] had died and I’m guessing this is what is happening now.

“It will only be clarified and confirmed when his sister takes complete control as far as I see it.”

Kim Jong-il Kim Il-song
Massive statues of Kim Jong-il and Kim Il-song in Pyong Yang (Image: GETTY)

Ruth Anne Monti, author of North Korea in 100 Facts, has previously suggested Kim’s health is ailing and that he needed help with walking.

She told Express.co.uk today: “Kim is seriously unhealthy.

“He’s quite overweight, smokes, drinks, and keeps a very rich diet.

Kim Jong-un family tree

“This is certainly not a healthy lifestyle.”

Chang told reporters yesterday: “I assess him to be in a coma, but his life has not ended.

“A complete succession structure has not been formed, so Kim Yo-jong is being brought to the fore as the vacuum cannot be maintained for a prolonged period.”

North Korea
North Korea is arguably the world’s most secretive country (Image: GETTY)

The speculation about his health follows reports of Kim’s regime having declared a bizarre “war on sex”.

The US-backed Radio Free Asia website earlier this month claimed six people – including four party officials – had been executed by firing squad after being accused of either pimping or buying sex at a public bathhouse popular among influential city residents.

One insider claimed Kim had given the order personally.