Makeshift camps of grass huts and tents stretch as far as the eye can see along the main road lending from here to the Red Sea, accommodating a rising tide of refugees from neighboring Ethiopia.

For almost 20 years, Sudan has been besieged by refugees from the wars and revolutions of its neighbors in the south and west. But the exodus from Ethiopia that is still under way has dramatically increased the number of refugees here to nearly 500,000 and threatened the country's economic, social and political stability.

The Sudanese have managed to settle about 42,000 refugees, according to a representative of the U.N. High Commissioner for Refugees, Said Halim. But, he says, that is "just a drop in the ocean."

While most refugees from Ethiopia stay in camps near the border, a substantial number moves west to Sudanese towns and cities, straining municipal and housing facilities to the breaking point and contributing to already roaring inflation.

Those who remain in the camp complain bitterly of hunger. "We are living like dogs," said one man at Um Guljar camp north of here as he displayed a basket full of white beans. Days of soaking and hours of simmering on scarce firewood had not softened them enough to be edible.

Suday, which is one of Africa's poorest countries, is not preparing an appeal to the world community for $50 million to help settle the refugees.

Most of the new refugees come from Eritrea, Ethiopia's northern province where secessionist forces have been involved in a protracted armed struggle against the government.

More than 250,000 Eritreans are estimated to have fled to Sudan. Other Ethiopian groups fighting the pro-Soviet government in Addis Ababa, notably the Tigrean and Oromo tribes of southern Ethiopia, have made their way across the 1,600-mile-long border into Sudan.

Over the years, the pro-Western government of President Jaafar Nimeri has made a valiant effort to settle the refugees. Some have been given 10 acres of farming land near new villages with reservoirs, roads, schools and clinics. Others have been settled at the edge of Sudan's great state farms on new irrigated land where cotton and sorghum are grown and where there is a crying need for workers.

But only one of the half dozen settlements near the eastern border -- the complex of villages at Qala En Nahal, with a population of 20,000 farming their own land -- has so far become self-sufficient, and that has taken nearly a decade.

More typical are the camps at Khasm El Girba and Um Guljar, both along the road from here to Port Sudan on the Red Sea, that live off World Food Program donations. Sudanese refugee officials say that in addition to the staple sorghum, insufficient quantities of oil, salt and milk powder also arrive irregularly.

At Um Guljar, tuberculosis has increased so dramatically over the past year that one of the Eritrean medical assistants, who works at the poorly equipped tiny clinic, described it as "a dying community." The long line of pot-bellied children and emmaciated elderly men assembles each morning at Um Guljar, the worst of all the camps, but illnesses related to malnutrition haunt all the refugee centers.

The refugee doctor in the little grass and bamboo hut at Um Guljar is a medical student with just one year to go to graduation. Earlier hopes of financial aid to finish his studies have been buried under the relentless daily procession of the sick he can sometimes help, but rarely cure. His Ethiopian nurses and medical assistants have left in recent weeks. cForged passports are on sale throughout the refugee community, and in desperation the educated are fleeing to West Germany, away from the task of helping the Sudanese administer these camps.

In addition, more than 30,000 United Nations travel documents have been issued legally to the refugees. The majority have gone to the Gulf states to look for work they can not find in Sudan.

In stark contrast to the sick, hungry, purposeless refugees in the camps and settlements on the eastern border is the Eritrean camp of Solomuna, in the Red Sea desert 10 hours drive by truck south of Port Sudan.

Solomuna has 11,500 inhabitants and no one has left in the 15 months since it was set up. Two-thirds of the inhabitants are children, including 350 orphans under the age of 7. Another 2,000 -- mostly men -- are handicapped by war injuries.

But in one of the most inhospitable of natural habitats, the Eritrean People's Liberation Front has created a town that is a tribute to the resilience of the human spirit. Everyone works. Tiny children water a tomato plant carefully shaded from the sun by a thorn screen. In the "revolutionary school" the 3,000 boarding children whose parents are in Eritrea sleep in the open. They study science, mathematics and three languages under 100 teachers with books printed inside Eritrea by the front.

Handicapped men swinging around on crutches make bookcases, cupboards and cooking utensils out of spent Soviet shells and empty Soviet ammunition boxes captured in Eritrea. They have built solid rock houses and criss-crossed the valley with wires linked to their electric generator. They make sandals, repair watches, learn to type and paint in oils horrific pictures of recent Ethiopian history.

In a small, crowded community centers in back streets in Khartoum and its sister city of Omdurman, the Eritrean front and the much smaller Tigrinia Peoples Liberation Front also fight to keep their communities together.

They have organized courses for adult literacy for the thousands of unsupported women who have become prostitutes, as well as a weaving cooperative, dancing and political education. Food and drink are provided by the fronts.

Abdel Rahman el Bashir, Sudan's refugee commissioner, says he is confident that land, work and a rural infrastructure can be provided for the refugees of peasant background, but much more is needed for the new urban refugees.

"Many of these people are the elite," Bashir said. "We cannot let a whole generation be lost. The English-speaking countries of the world have a moral obligation to help these people."

But as the U.N.'s Said Halim says, "No one has yet come up with a solution to the problem of urban refugees -- it is simply too big and too expensive for any one country to handle."