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Never-before-shared accounts of time within the deadly camps revealed a strategy to control the population through terror, with many worked to death for supposed crimes as petty as singing to South Korean pop music. Thousands of malnourished and starving inmates are subjected to extreme forced labour and beatings by cruel agents of the Ministry of People’s Security (MPS), leading to the deaths of large numbers of prisoners, according to the research. The Committee for Human Rights in North Korea (HRNK) identified two distinct types of camps operated by Kim’s government: penal labour colonies, used to “forcibly disappear” anyone even suspected of questioning Kim’s dictatorial rule, and long-term prison labour facilities. The brutality of the political penal colonies are well documented, even though the regime denies they even exist. But far less is known about the prison labour camps known as kyo-hwa-so - meaning “a place to make a good person through education”.

Satellite images show North Korea’s shocking gulags Wed, February 7, 2018 North Korea operates two systems of arbitrary detention and political imprisonment. Both systems feature forced labor and brutal conditions, leading to high rates of deaths in detention in both systems Play slideshow HRNK 1 of 26 Map of prison camps in North Korea

HRNK/GETTY Inside North Korea's gulags: The regime runs more than 40 brutal “re-education” camps

The grossly inadequate food rations keep prisoners in a persistent state of hunger and malnutrition HRNK report

But through new research and using satellite imagery, HRNK has managed to lift the veil on these secretive facilities, which are designed to instil fear into ordinary North Koreans by jailing them for minor criminal offences or attending public gatherings not authorised by the state. UN experts estimate at least 70,000 North Koreans are imprisoned in the prison camps, though the exact figure is impossible to determine. And HRNK, a US-based leading human rights group which works to raise awareness of abuses in North Korea, has identified more than 40 of the facilities spread across the hermit state. One of the oldest camps is located in Kaechon City where between 4,000 and 6,000 prisoners are forced to operate dangerous heavy machinery and use toxic chemicals to produce textiles and leather for products including shoes and military holsters - some of which are exported overseas.

HRNK The grim Kaechon City prison camp is home to between 4,000 and 6,000 inmates

The report says: “Prison hygiene was reportedly appalling and food rations were inadequate, leading to high rates of death from malnutrition-related illness.” One of the prisoners, who HRNK interviewed in 2002, was imprisoned there after she was reported to police for singing a South Korean pop song at a private party. The camp at Chung-san is a series of detention facilities, each of which hold some 500 to 600 inmates. Because of its rural location, prisoners are sent to work in fields or rice paddies and tend livestock.

HRNK Prisoners who die from overwork at the Chung-san camp are buried in unmarked graves near the prison

Inmates are fed next to nothing and those who can not keep with the relentless work are beaten. HRNK reports there was a large number of deaths at the Chung-san, and the bodies of prisoners who died in the camp were disposed of in unmarked graves on a hill close to the camp. And the overcrowded camp at Jongo-ri houses a large number of North Koreans who were caught after fleeing over the border to China. It was initially a facility for male prisoners, though was expanded to accommodate women after 2008.

HRNK An "extremely high" number of inmates die in the Jongo-ri camp

Prisoners are forced to mine copper and iron, cut logs and make bricks. A former inmate told HRNK the rate of deaths in the prison from forced labor and below subsistence level food rations was "extremely high”. HRNK says a lack of food and arduous working conditions are typical in every re-education camp. The report says: “The grossly inadequate food rations keep prisoners in a persistent state of hunger and malnutrition.

“Prison labor is arduous and sometimes dangerous manual labor. “Prison work units have production quotas and failure to meet the quotas can frequently result in a further reduction in food rations and even beatings.” But North Korean police officials do not deny the existence of the kyo-hwa-so camps, and often make ridiculous claims about the quality of the conditions. Colonel General Jung Young-wook of the MPS has reportedly claimed prisoners are provided with food, adequate winter clothing and top-notch medical care.

NPR.ORG Kim Jong-un's Ministry of People’s Security is responsible for running the re-education camps

And the study quotes an MPS Lieutenant General as saying: “When prisoners in the kyo-hwa-so have dinner we let them study and watch TV. “About twice a week we also show them interesting TV and soap operas or films... now there is a TV in every room. “We also provide newspapers, magazines and the state newspaper Rodong Shinmun.” The report was authored by North Korea expert and veteran human rights activist David Hawk and Amanda Mortwedt Oh, HRNK’s project officer in charge of satellite imagery analysts.