Grafting in the blazing sun, Kim Jong-un ’s child slaves load heavy rocks into sacks as others mend railway tracks with hammers.
Taken out of lessons and forced to carry out back-breaking work, they toil for up to 10 hours a day.
The footage of North Korea ’s human rights abuses, uncovered by the Daily Mirror, will shock the world.
Yet in his palace hundreds of miles away, despot Jong-un enjoys a life of luxury and thinks nothing of enslaving innocents as young as five.
Michael Glendinning, of the European Alliance of Human Rights in North Korea, said: “The footage obtained by the Mirror is startling in its documentation of one of the worst abuses the North Korean state inflicts – child labour.”
A network of brave informers used hidden cameras to secretly record footage over the course of this year.
In one film – shot in the north east province of Ryanggang – a forlorn lad of around eight or nine, wearing an England football shirt, is ordered to break rocks at a cliff face.
Girls pair up as they struggle to lift heavy loads into piles. One young boy winces under the strain of his work.
Teachers shielding their faces from the glaring midday sun bark orders at other youngsters bent double from lugging sacks as big as their bodies.
Mounds of massive sandstone broken up by the dusty child slaves can be seen piled high. Their miserable existence is in stark contrast to that of tyrant Jong-un.
Born into a dynasty of iron rule, he benefitted from a first class education in Switzerland before taking power in 2011 after the death of his father Kim Jong-il, “The Dear Leader”.
He quickly started spending millions amassing an arsenal of missiles and nuclear weapons. After a fourth nuclear test in January, threats were directed at South Korea, US and even Britain.
American officials last week confirmed the regime’s capability of attaching nuclear warheads to missiles.
Yet despite wanting to appear a great power, the nation flouts international law by exploiting its children.
Officials refer to the tasks as “team-building” for the good of the country.
With a population of more than 24 million, human rights experts warn that millions of children are being used as slave labour every day.
Activists claim some from poor backgrounds have not been to school in a year. And child workers face brutal beatings if they fail to complete work.
This week, Britain’s UN ambassador Matthew Rycroft described forced labour in North Korea as “modern slavery”.
A 2014 United Nations report detailed rights abuses in North Korea by a “state that does not have any parallel in the contemporary world”.
Further footage obtained by the Mirror graphically exposes the regime’s cruelty. In Chagang Province, in the north of the country, tiny children form a chain gang along a railway line.
With hammers and axes, they smash up large rocks into fragments to be laid across the tracks.
A newly built station, understood to be along the Hyesan Manpho Chongnyon Line, otherwise known as the Pukpu Line, can clearly be seen.
Another shot of the horizon shows dozens of children working in the production line. The sounds of rocks being broken and steel bashed on metal tracks echoes around them. Two little girls crouch together in silence as they struggle with their work.
Human rights organisations have reacted with horror after looking at our findings. Mr Glendinning said the nature and duration of work assigned to children broke a series of domestic and international laws.
Calling for the international community to act, he added: “Millions of North Korean children are forced to work in back-breaking roles that rob them of the chance of a happy childhood.
“The impact of the work on their physical development, their physical and mental health, and on their education can’t be understated.
“The footage corroborates our own research on child labour, which found that children routinely experience forced labour.
“However, it’s not just physical abuse experienced by children – it’s also psychological. Children are subjected to self-criticism sessions and ideological indoctrination.”
The agency also expressed concerns over “physical injuries, malnutrition, exhaustion, growth deficiencies and lasting psychological problems”.
In stark contrast, children at schools for the elite are seen smiling and singing on film as their proud parents look on. Standing in front of teachers dressed in black suits, they learn to recite verses giving praise and thanks to Jong-un.
The school is in Kanggye City, capital of Chagang Province – just miles away from where slave children are working in gangs in the blazing heat.
Music plays in the background as children in smart clothes perform a series of regimented movements and exercises. Teachers stand at the front of the group directing every move. The camera pans to smiling parents who are watching on from the school gates.
North Korea remains one of only a handful of states not to be a member of the International Labour Organisation, which “seeks the promotion of social justice and internationally recognised human and labour rights”.
Pastor Kim Sung-eun is director of Caleb Mission and helped hundreds of North Koreans escape to the South.
He said: “The footage uncovered shows many of the human rights abuses taking place in North Korea every day. The international community should stand up and act at once.”