A North Korean state media documentary has claimed Kim Jong-un has "withered" out of concern and hard work for his people, revealing that his body has been left so weak that he struggles to walk down a set of stairs. 

The documentary – 2021, A Great Victorious Year – appears to suggest Kim's dramatic weight loss last year was linked to his sacrificial sense of duty to the population, feeding into his growing cult of personality, reported NK News, the Seoul-based website that revealed the new footage. 

Kim Jong-un on horseback. Picture / Supplied 

The video sticks to long-held state media traditions of showcasing Kim's military leadership and prowess on a white steed, but the focus on his stark weight loss also reflects the country's hardships over the past year because of the Covid-19 pandemic, international sanctions and widespread food shortages. 

It also coincided with the mysterious shrinking of his once hefty physique, raising concerns about his health and ability to lead. 

State media documentaries are normally released annually and the latest reinforces official narratives that Kim is simply eating less "for the sake of the country". 

In one of the most striking scenes, he gingerly walks down a half-constructed staircase on a Pyongyang building site, carrying a blue umbrella and flanked by attentive officials. 

His white shirt and black trousers hang loosely around his frame as a narrator with a quivering voice says that he "showed us his fatherly side by doggedly braving snow, rain and wind while taking on the fate of the nation and people like his own children". 

In a translation provided by NK News, the narrator adds: "His body completely withered away, and he showed his motherly side by greatly suffering and worrying to realise the dreams of the people". 

The government's decision to seal the borders to keep out Covid-19 and a shortage of grain caused by bad weather raised fears last year that the already malnourished nation could be heading towards famine. 

The UN's Food and Agriculture Organisation has estimated North Korea was short of 860,000 tonnes of food last year alone, the equivalent to about 2.3 months of food. 

Kim's call for another "arduous march", echoing the phrase used in the 90s when as many as 3.5 million people starved to death amid economic mismanagement and a series of droughts, reinforced North Korea's desperate situation. 

The film gives a nod to the country facing its "worst-ever hardships" and "challenges" last year, including a national "food crisis". 

But it also retains state media's fondness for triumphal and militaristic footage that projects the army's strength and boosts Kim's image as a revered leader. 

The carefully choreographed video opens with Kim gazing thoughtfully into the horizon on horseback as the sun rises over a beach and small waves roll into the shore. 

The theme of his horsemanship continues as he is seen riding through a forest in summertime, alongside senior military officials, before the footage cuts to more dramatic scenes of tanks lining up in a field for a firing practice that engulfs them in white smoke. 

Kim gingerly tackling some half-finished stairs. Picture/ Supplied 

The emphasis on conventional warfare follows a prolonged show of military might last month after Pyongyang clocked up a record seven major weapons tests, the most in a calendar month. 

The country's military build-up has continued unabated despite its economic woes. North Korea has also threatened to abandon a self-imposed moratorium on launching long-range and nuclear weapons, blaming "hostile" US policy for forcing its hand. 

Kim's physique has long prompted debate about chronic diseases that could impair his ability to lead. 

Personal details about the reclusive leader are highly classified, and intelligence agencies keep a close watch on his weight fluctuations for any signs of illness that could bring about a sudden change in leadership or instability in a country known to be developing nuclear weapons. 

Kim, reported to be a heavy smoker and drinker and fond of culinary delicacies, has piled on the kilos since rising to power. 

According to one assessment by South's National Intelligence Service, he was 90kg in 2012 but had ballooned to 140kg by 2020. 

- by Nicola Smith, Daily Telegraph UK