As a citizen of one of the world's poorest countries, Tae Gun would not have stood out in the North Korean marketplace where she frequently scavenged for food. But as starvation and disease loomed, she realised she would have to do something far more dramatic than search for scraps to survive.

Like thousands of other North Korean refugees, she contacted a group that offered to take her across the border into China where, she was told, she would be sold into wedlock. It was a price she thought worth paying. Surely in China, where even the peasants are able to afford white rice, life would be better.

The family that took Tae in near the Chinese-North Korean border treated her well. But it was not long before the police were knocking on her door during one of their periodical round-ups of refugees. Rather than face a return to North Korea and years inside a labour camp, she decided to flee again, only to be sold into a prostitution ring. Her final bid for freedom took her to Mongolia and, finally, the relative safety of South Korea.

With headlines dominated by the diplomatic standoff over Pyongyang's nuclear weapons programme, the humanitarian and health crises facing millions of ordinary North Koreans like Tae is in danger of being forgotten, aid workers have warned.

Tae Gun (not her real name) is one of three North Korean refugees featured in Je regrette d'etre né la-bas (I wish I'd never been born there), a new book about the North Korean refugee crisis by Marine Buissonnière, secretary general of Méldecins Sans Frontières (MSF), and MSF coordinator Sophie Delaunay.

Buissonnière, who was part of an MSF team based in North Korea for three years from 1995, says little has changed since the medical group, exasperated that its services were not getting through to the people who needed it most, decided to pull out of North Korea in 1998. "Six years later I hear the same stories", Buissonnière, now based in Seoul, said during a visit to Japan. "I don't see any major changes."

Many of the refugees offered medical care and counselling by MSF's Seoul office were victims of the 1995 floods and the resulting famine, which killed up to 3 million people over 4 years.

Its nuclear ambitions aside, observers say North Korea's economy remains at breaking point, and the gap between the haves and the far more numerous have-nots has widened since the introduction of limited economic reforms.

"The international press reports mostly on the nuclear issue and other political aspects of North Korea", Kathi Zellweger, of the Catholic aid organisation Caritas, said in a report after a recent trip to North Korea. "But it is important to remember that there are millions of people there who lead an ordinary life, but one marred by a grim struggle for survival."

By North Korea's own admission, the health of its 23 million people is in a parlous state. In 2002, average life expectancy had dropped by 5.5 years since 1993 to 67.2 years, according to a report issued this month by the UN population fund and the North Korean population research institute. South Korea's national intelligence service attributed the decline to knock-on effects of the 1995-99 famine.

At 64.9 years for men and 69.3 years for women, North Koreans' lifespans are, on average, 11-12 years shorter than their counterparts in the prosperous, democratic South. The maternal mortality rate has almost doubled since 1995, from 35 to 67 per 100,000 live births in 2000 - three to four times higher than in the South.

According to the UN World Food Programme (WFP), 6.5 million North Koreans - mainly women and children - were in need of food assistance in 2004.

Despite improvements, child malnutrition remains a concern: about 9% of children suffer from acute malnutrition, while chronic malnutrition is said to affect more than 45%.

One study found that 70% of those who survived the famine were stunted, and a quarter underweight.

Although surveys conducted between 1998 and 2002 by the North Korean government, the WFP, and UNICEF, showed significant improvements in children's health, children are still dying from diarrhoea and respiratory diseases associated with malnutrition.

On a wider scale, North Korea suffers from massive shortages of medicines and equipment. Large hospitals have no running water or heating. A major outbreak of, say, malaria, many experts agree, would cripple its already crumbling health infrastructure.

Norbert Vollertsen, a German doctor who worked in North Korea for 18 months, says little had changed since he was expelled from the country in December, 2000, after going public about the appalling conditions he witnessed.

Citing eyewitness reports from colleagues who recently returned from the North, Vollertsen said minor improvements in major cities contrasted with a desperate situation in other parts of the country.

"Although there has been some improvement in Pyongyang and in cities like Nampo and Wonsan due to monitored foreign aid, the situation in the countryside is getting worse because of the introduction of limited Ã??capitalistÃ?¢ reforms", he told The Lancet from Seoul.

"People cannot afford medicine or even healthy food because of enormous inflation, and they have to bribe doctors to get special treatment. Hospitals in the countryside still have no running water, soap, disinfectant or narcotics."

As a member of the medical group German Emergency Doctors, Vollertsen gained a closer look than most outsiders at the reality of North Korean health care. He and a colleague were feted by the government after performing surgery on a badly burned man using grafts of their own skin. But disillusionment soon set in.

In his book, Diary of a mad place, he documents the "unbelievable" deprivation he witnessed in hospitals and orphanages around the country - no scalpels or antibiotics, no operating facilities, just broken wooden benches with beer bottles used as vessels for intravenous drips. He witnessed operations performed without anaesthetic.

Poverty, malnutrition, and political repression have also left many North Koreans with serious psychological problems.

"People are suffering from burn-out syndrome", Vollertsen says. "They know there's no hope of change, so diseases such as alcoholism, as well as suicides, are common."

Even those who manage to escape must contend with the fact that their actions may have endangered the welfare of relatives and friends who stayed on. After years as citizens of a strictly conformist state, they must also learn how to live a life that little resembles the one they left behind.

As a result, many of the 5,700 North Korean refugees in South Korea suffer from post-traumatic stress disorder, MSF's Buissonnière said. Though they receive "substantial" financial and practical help from the government in Seoul, little is done to help them overcome their psychological suffering.

"They feel rejected, which puts them in an incredibly harsh psychological situation. Guilt prevents them from restarting their lives."

International agencies with a long-term presence in North Korea say their work there is undermined by obstructionist local authorities.

According to Buissonnière, MSF had 12 staff supervising 1,100 health structures in four provinces. Logistically and politically it was almost impossible to move around, as aid workers we're required to give several days' notice every time they wanted to visit a medical facility.

"All these elements made it very difficult to simply visit the places were supposed to monitor", Buissonnière said.

In its final 18 months in North Korea, MSF provided US$10 million of assistance, but the organisation's doctors had little idea how it was being used.

"We could not see where it was going", recalled Buissonnière. "The overall circumstances made it impossible for us to assess who we were reaching, if we were reaching anyone. We had a feeling that assistance that we were giving was not assisting the most vulnerable. We held a strong belief that we were contributing to feeding the regime."

A recent outbreak of avian influenza showed what could be achieved in North Korea with greater bilateral and multilateral cooperation. As authorities launched a cull of more than 200,000 chickens, WHO staff worked alongside local doctors, teaching them laboratory diagnosis using UN-supplied diagnostic kits.

But re-engaging with North Korea in the way Buissonnière and Vollertsen believe is crucial to its people's health could be some way off, particularly now that the regime is rumoured to be preparing to conduct its first-ever nuclear test. Yet they remain hopeful. Buissonnière concluded: "If we could have the ability to access the needs and work directly in contact with the population, we would certainly consider going back. We are not closing the door."