But a Norwegian paediatrician working for Unicef, the children's agency, recently found a 10-year-old boy lying on a rural road, too weak to walk. "This shows that the scale of the disaster goes much deeper than we realise," said Marie Staunton, deputy director of Unicef in Britain, who has just returned from a visit to North Korea.
Ms Staunton saw for herself at a children's home in the northern city of Huichon. Five-year-old Kim Pook Nan had lost both her parents - her father was drowned in the floods that devastated the country in 1995 and 1996, her mother died of diarrhoea in July. Stick-thin legs protruded from her pink dress, and she had reached the final stage of malnutrition, according to a Unicef nurse.
In another room was Ri Un Huyang, aged two, whose parents had also died in the floods. Her grandmother handed her over to the home after running out of food at the beginning of April. The little girl had gained weight since being fed high-energy milk from Unicef. The children had been made to sit up for the visitors, but as they were hurried out of the room another two-year-old girl, Kim Su Sim, collapsed from malnutrition.
United Nations agencies estimate that about 80,000 children are now in imminent danger of dying, and that a third of North Koreans under five, some 800,000, face permanent physical and mental damage from malnutrition. It is figures such as these that have persuaded the regime to allow more access to foreigners - "We did not know of the existence of a network of children's homes until this month," said Ms Staunton - and to relax some of its Stalinist controls on private trading and the movement of its citizens around the country.
Each step, however, has come reluctantly and apparently too late to prevent many lives being lost. The government admits that the daily food ration has fallen from 700 grams in the early 1990s to only 100 grams, barely a third of what is needed to maintain health. Villagers have been eating grass, roots, bark and seaweed in desperate efforts to make up the shortfall.
Floods have been followed this summer by drought, which has destroyed some 70 per cent of the maize crop, and rice plants are shrivelling in the paddies for lack of water. The UN calculates that North Korea needs 3.8 million tonnes of grain just to avoid starvation, but has only 2 million. If the crucial rice crop, due to be harvested in October, also fails, the country faces mass famine unless aid arrives in time.
Young children and the elderly are the first to suffer when food is short, but Ms Staunton said Unicef workers were also beginning to see severely malnourished teenagers. This is another sign of the depth of the problem, as they are old enough to forage for themselves and often help to keep other family members alive.
The effects of natural disaster have been compounded by Communist mismanagement. The authorities themselves say the economy has shrunk by half since 1990. "North Korea used to have a functioning economy and social system, but no longer," said Ms Staunton. "Even soap has to be imported. You have hospitals with no drugs and superb roads with no traffic, because they have run out of fuel."
The UN World Food Programme, which has just been allowed to operate in all of North Korea's nine provinces, has appealed for 700,000 tonnes of grain immediately. Unicef is stepping up supplies of medicines and high-energy milk, and has trebled its appeal target to $14.3m (pounds 9m), but so far it has received only $3.5m.
One reason for the world's slow response is the dogged recalcitrance of the North Korean regime, whose isolation has eased little since the late "Great Leader", Kim Il Sung, was succeeded by his son, Kim Jong Il, three years ago. While grudgingly admitting that it needs help, Pyongyang resists giving anything in return.
On Friday, efforts to bring the two Koreas together with the United States and China to declare a formal end to the war that devastated the peninsula more than 40 years ago were shelved until next month. North Korea refused to drop its age-old demand that American troops leave South Korea, and insisted that the conference discuss a peace treaty only with the US, excluding its "puppet", South Korea.
According to South Korean sources, this was the North's way of extracting more food assistance from the US. It reflects the bloody-minded spirit - officially enshrined as juche, or self-reliance - which has helped North Koreans stay alive, but which could soon condemn them to a lingering death.Reuse content