The international aid group Doctors Without Borders says at least half of all North Korean asylum seekers have probably been psychologically damaged by their attempts to leave their homeland.

Doctors Without Borders says the ordeal of fleeing North Korea causes widespread psychological damage to those who attempt it.

The group, known by its French initials MSF, helps about one hundred North Korean defectors here in Seoul. The organization says 70 of them have mild to severe psychological trauma. Their symptoms include alcoholism, anti-social behavior, inability to sleep or concentrate, and domestic violence.

Tom O'Connor represented MSF this week at an international conference on North Korean human rights and refugees. He makes a sweeping projection about the mental health of the refugees.

"We can reasonably say that more than 50 percent of that [refugee] population - and that's something that we strongly believe in MSF - suffers from psychological illnesses," he said.

He says that assessment is based on interviews with North Korean refugees both in South Korea and in other countries, such as China.

North Korea is one of the poorest countries in Asia, and has been on the brink of famine for nearly a decade. It also has one of the world's most repressive governments, which frequently imprisons not only those suspected of political crimes, but also their families. The people have almost no access to outside news media, arts or entertainment.

About 100,000 North Korean refugees are believed to be hiding in China, having crossed over the border to escape hunger and persecution. For most, the goal is to reach a third country, usually South Korea. Getting to South Korea involves a hazardous trip across the border, months and even years of hiding in China, all the while struggling to find food and shelter.

However, China treats North Koreans as economic migrants rather than refugees, and sends them home, where they face harsh punishment or even death. Many refugees make more than one attempt to flee before finally reaching South Korea.

Human rights groups say the majority of the asylum seekers are women. Mr. Connor says whether they are caught or not, they face many ordeals.

"Crossing the border is physically a trauma, because you can be shot at - being chased down systematically by the police, being sold to Chinese soldiers, being raped, being pregnant, having your baby killed," he said. "Being forced to sell your children, when you have, because they're illegal. Being forced to see your child dying, or murdered, in front of your eyes."

Female defectors provided this week's conference in Seoul vivid and dramatic testimonies of the horrors they faced.

Park Sun-ja says that after being repatriated following one attempt to flee, she witnessed newborn babies being killed in a North Korean prison.

Ms. Park says in the early stages of their pregnancies, women were given injections to induce miscarriage. She says a woman in her final trimester was allowed to give birth, and the baby was suffocated with a wet towel.

Kim Choon-ae says she was kidnapped in China by human traffickers - something she says happens to many North Korean women. When she and other women fought back, Ms. Kim says they were turned over to police and forced home.

Ms. Kim says in a North Korean prison, the staff treated women prisoners as sex slaves.

Psychologists say the full damage of the refugee experience sets in only after North Koreans arrive in a safe country.

And often, being in South Korea creates new problems. The North Koreans find it difficult to adjust to the high-technology, high-pressure capitalism of the South. They struggle to find jobs, and because of weaknesses in the North Korean education system, they usually need extra training to meet job qualifications.

Many also face discrimination from South Koreans.

Ahn Hyun-nie, who is with the psychology department at Pusan National University, says many refugees experience what is called Complex Post Traumatic Stress Disorder.

Very often, the symptoms appear as personality or behavior quirks, such as being hot-tempered, which makes the underlying trauma hard to diagnose. Ms. Ahn says those problems contribute to the discrimination the refugees face.

"Being seen as having a difficult temperament or a difficult personality decreases the chances of building and extending their social support, once they arrive in South Korea - something which is very crucial in their healing process," she said.

Mr. O'Connor, of Doctors Without Borders, says many South Korean health professionals are reluctant to treat North Korean refugees.

"Maybe because they are afraid of seeing something which reminds them of their past," he said. "Maybe it's too disturbing, because their brothers are too close. Maybe because they don't know how to handle all this suffering."

Only about 6,000 North Koreans have reached the South since the end of the Korean War in the 1950s - more than half of them in just the past three years. However, recent polls show more than half of all South Koreans perceive the refugees as an economic and social burden.