"Some didn't want to go to the political offence asylum, so they swallowed chopsticks and needles," he declared. "When they pleaded because of the pain in their stomachs, no medical treatment was offered. We were beaten by the prison guards several times a night and treated like animals." He pleaded that he had only crossed the border to get hard currency for the party and was released after four months. He escaped again and this time reached South Korea after a year on the run travelling through China, Myanmar, Vietnam and Thailand, where he got a temporary passport.
"North Korea is a totally different country from South Korea," he said. "Reunification must be done gradually. There must be economic co-operation first. Before East and West Germany were united there were many exchanges. We have to narrow the gap through regular talks and exchanges."
When Lee Min Bok fled across the Tumen River from North Korea he thought China was "paradise" as the shops were full of food. The 43-year-old agriculture researcher from Pyongyang was stunned when he reached Seoul, with its traffic jams and high buildings topped with giant TV screens. "The gap between the two Koreas is so huge, it's indescribable," he said. "But what I couldn't get over were small things, such individually candies, and this sort of thing." He picked up a toothpick encased in paper from the restaurant table where we were having tea. "Taking care of the smallest things in the world meant to me this was a humane society. Only high officials in North Korea had toothpicks."
Mr Lee was also returned by the Chinese when he first defected in 1995. "I had spent all my life in North Korea working on how to solve the food shortages and developing related technologies. The problem was the collective system. As an experiment I tried Chinese methods and got an increase in output of 300-500 per cent. I wrote a letter to Kim Il Sung (then the North Korean leader). Top officials of the communist party came and said, `you are right but don't do it any more or you will get hurt'." He was put in the political prison after his capture. "I was made to sit up all night and not allowed to the toilet. They did not give me any food. My finger and toenails stopped growing because of malnutrition. My weight dropped from 64 to 40 kilograms in two weeks." He, too, was eventually released and succeeded in his second attempt to escape.
The action of the Chinese authorities in returning North Koreans is being challenged by the Commission to Help North Korean Refugees, set up in Seoul last year with the backing of Christian groups. The number of "escapees" living in fear in China is estimated by the South Korean government at 30,000 and by civic groups at 300,000. The commission secretary general, Dr Kim Sang-chul, said that China was wrong in treating them as illegal migrants rather than refugees. Food migrants in other countries were not punished when caught, he pointed out, but North Koreans defectors were treated as political offenders, and subject to prison terms or even execution. With relations between China and North Korea improving with Kim Il Sung's visit to Beijing last week, he saw little chance of a breakthrough arising from the summit.
A senior western diplomat said it was common knowledge in Seoul that the South Korean aim is to underpin the regime in Pyongyang to prevent it collapsing, because it could not handle the vast number of refugees which might flow from a country of 23 million if it was suddenly plunged into chaos.
Many elderly South Koreans hope that the summit will at least ease the distress of separated families. Millions of North Korean refugees fled to the south to escape communism before and during the Korean War. They found themselves stranded when the armistice came in 1953. The first generation of separated families is now fast dying out and the easing of tensions has come too late for them.
Mr Dong Young Cho, who runs the "Korean Assembly for the Reunion of Ten Million Separated Families" has little expectation of a change of attitude by North Korea, which has refused even postal contact between separated relatives. In 1985 there was an official reunion for 50 families but since then nothing has been allowed. The only way to make contact with lost relatives was by paying ethnic Koreans from China who had access to North Korea to bring letters to relatives. Last year there were 637 deliveries of letters, and 469 the previous year. Only five secret family reunions had been achieved in North Korea, at great risk.
Now 77, Mr Dong was separated from his parents and two bothers and sisters by the Korean War. In his Seoul office, lined with thousands of files, he told me that in December 1998 he received a letter from a woman in North Korea. "She wrote, `I think I am your sister', and told me she had raised two children and that her husband had passed away. You can't imagine what it felt like. It was like a dream. But I found that she was the only one left alive. I feel so sad, it really hurts, that I couldn't see my parents before they passed away." He is hoping to get his sister, now 72, out of North Korea through official channels. "If I try the unofficial way it could imperil her life," he said. "If she was caught by the Chinese government and sent back, she could go to jail or concentration camp."
Hong Kun-sik, also 77, the youngest of seven brothers and sisters who remained in the North, is in despair that any of them are alive today. "I often try to imagine how they have changed in their features and in their minds, but I sometimes can't remember their faces," said Mr Hong, president of the Association of Lost Home Towns.
"I have been homesick for 50 years. My life has been in vain since the age of 23 when I foolishly left North Korea. In the South among the second generation there are two types of children, A and B. The A type say `I was born in the South so I don't really care about the North.' The B type says `I was born in the South and my parents cried all the time about the North so I am interested.' I have two boys and two girls and they are all of the B type, I am happy to say."
He had no doubts about what he wants now. "I dream of the collapse of communism in the North. I have been waiting for 50 years. I am tired of waiting. I think reunification should happen right away."