On the day that he reappeared - apparently - after a three-week absence from public life, the focus of attention regarding Kim Jong-un dramatically turned to his wrists.

Marks on the North Korean leader's arms suggest he could have had heart surgery, say medical experts.  

After studying video footage of his visit to a fertiliser factory, they claim the marks show he has had a 'cardiovascular procedure', NK News reported.

The dictator chose to appear, after a 20-day exile, at the opening of a factory in Sunchon, where he cut an ostentatious red ribbon with a pair of very large scissors, dutifully passed to him by his sister Kim Yo Jong.

Only days ago, she was being talked of as his successor, given his status ranged, according to reports, from being in a vegetative state due to a botched operation, to actually having died.

The dictator was seen smiling, smoking and talking to aides at the ceremony and also touring the plant although, as ever, the authenticity of the photos could not be verified.

He also rode in a golf cart that looked strikingly similar to the one he used in 2014, when he returned to the public eye with a stick, again after a period out of the public eye.

Yesterday Donald Trump suggested he knew what had happened to Kim, hinting he was unwell as he said he hoped ‘everything will be fine’.

The US President said: “Kim Jong-un? I can’t tell you exactly. Yes, I do have a very good idea, but I can’t talk about it now.

“I just wish him well.”

Asked about reports surrouunding Kim, the President said: “I'd rather not comment on it yet. We'll have something to say about it at the appropriate time.” 

Speculation about Kim's health has been rife after he missed the birth anniversary celebrations of state founder Kim Il Sung on April 15.

The day is a major holiday in North Korea and Kim as leader usually pays a visit to the mausoleum where his grandfather lies in state.

He last made a public appearance on April 11 attending a meeting of the ruling Workers' Party politburo.  

A number of unconfirmed reports about his condition and his whereabouts followed, including one from vice director of Hong Kong Satellite Television Shijian Xingzou who claimed he was dead.