For years, Guang-il Jung was haunted by a nightmare in which he was leaving a prison camp. Prisoners stretched out their emaciated arms to him, begging him not to leave them to die.

Waking, however, brought little relief. He knew that the prison existed and he knew, intimately, the tortures to which the prisoners were being subjected. He too had been starved, beaten and endured forced labour for three years before his eventual escape into South Korea.

Mr Jung, 46, was one of two North Korean defectors who yesterday spoke to The Times before giving evidence in Parliament of the human rights abuses they had suffered.

The rare glimpse they provided of life inside the notoriously closed and secretive regime was given in the hope of refocusing international attention, long distracted by the country's nuclear ambitions, on North Korea's human rights abuses.

Next month, North Korean officials will face their first review by the United Nations Human Rights Council. Pyongyang has already submitted a 20-page self-analysis in which it declared that it had no human-rights problems except the "hostile policy" of the international community towards it.

Mr Jung disagrees. He was a businessman, dealing with Chinese and South Koreans, when he was abruptly arrested in 1999 and accused of being a spy. "I didn't see it coming," he said, through a translator. "North Koreans hear whispers about the gulags. But only that the people who disappear into them never come back. That, and the fact that if someone disappears, three generations of their family is punished too."

What he did not know, he was soon to find out. He was put in a room, he said, with no windows and no light. When he asked why there were no guards patrolling he was told, "this is a place for you to die. There is no need for guards here."

His hands were tied behind his back, and he was hung from a wall by the rope. "After an hour like that, your chest starts to swell," he said. "The pain feels as if you are about to explode. That's why they call it 'dove torture', because doves have swollen chests too."

At intervals, he would be taken down and asked to confess. When he refused, he was hung back on the wall. He begged, unsuccessfully, to be allowed to use a toilet. "It was July when I was arrested," he said. "I was wearing short sleeves and weighed 71 kilos. When I finally gave a false confession to end it, it was winter. I was freezing. I weighed 36 kilos."

The human rights organisation Christian Solidarity Worldwide believes that statements like Mr Jung's, along with the material collected by human rights organisations in anticipation of the Human Rights Council's review, prove that the international community is duty-bound to establish an international commission of inquiry into crimes against humanity in North Korea — ranging from routine degradation of women to the torture of political prisoners and persecution of Christians.

Lee Sung Ae (not her real name) is one such Christian. She told The Times that her husband died of malnutrition. When it began to look certain that her four young children would follow him, she fled into China, where she was converted to Christianity and given aid to return.

She had converted a small circle of friends before a suspicious neighbour called the police and she was arrested. "They pulled out my nails, one by one," she said. "And then they started on my teeth." They were trying, she said, to extract the names of those she had converted but she refused.

Without a trial, she was sentenced to four years in a re-education camp. Worse than the starvation she endured there, was the fear she felt for her children. "I felt like my heart was bleeding for them", she said. "When someone goes into a gulag, all their possessions are reposed. My children, made homeless, begged on the streets for two years before fleeing to China. The eldest was fifteen, the youngest seven. Soldiers keep up a 24 hour patrol along the border but sometimes they have to take short breaks. That's when the boys fled for their lives." One later died, she said, at the hands of the police when they made a brief return to North Korea.

It is estimated that 30,000 North Koreans have fled into China. Many more have been forcibly returned to face punishment. Last month, the UN envoy to North Korea, Vitit Muntarbhorn, condemned the fact that another 400,000 had died in the country's system of prison camps, either by execution or of a combination of malnutrition and exhaustion brought on through forced labour. Mr Muntarbhorn has been denied access to North Korea, and the country's policy of isolation make it impossible to confirm the details of individual witness reports, leading some to doubt the possible scope of international intervention.

Carla Ferstman, director of Redress told The Times: "If a commission were to be set up it would need full and unhindered access to North Korea in order for it to be effective, and it is difficult to see that happening."

Others are more optimistic. According to Clive Stafford Smith, the British human rights lawyer who has defended Guantanamo inmates, the very fact of North Korea's refusal to co-operate in the review would reinforce the appearance of guilt.

Mr Jung knows something must be done. After his release he felt compelled to speak out. The international community, he said, "is talking a lot, but there is no action to help those in the gulags. They are crying out for help but also for hope. If they knew that there were people bearing witness and that the outside world was listening, they might have just enough hope to cling on to life."

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