Packed in Soviet cargo planes, battered blue buses and aging dump trucks, Ethiopian peasants by the hundreds of thousands are leaving the barren and overcrowded northern highlands and are being delivered to verdant southwestern lowlands where the grass is often taller than they are.

"It is quite staggering," said an Australian diplomat who has been ushered through the resettlement areas, "to stand there and look out at thousands upon thousands of kilometers of virgin agricultural land in a country that has been farmed for 3,000 years."

The great Ethiopian famine, which has claimed the lives of at least 300,000 people and threatens another 7.75 million, has triggered a prodigious logistical and organizational effort by one of the world's poorest countries to address mass starvation by moving peasants to a new land, where they have a better chance of feeding themselves.

That, at least, is the Ethiopian government's professed reason for a resettlement plan that has moved about 120,000 people in the past six weeks. It expects to move 1.5 million by the end of 1985 and 3 million by the end of the decade.

As soon as it began, however, the resettlement program of Ethiopia's Marxist military rulers became a symbol of ideological conflict between western donor nations, which are providing hundreds of thousands of tons of food, and the Soviet Union, which is supplying an estimated $3 billion worth of arms.

Ethiopia is besieged by famine and by civil war, both of which are wreaking havoc in the northern highlands. Any attempt to resolve the famine by moving people off the highlands is bound to be linked to the war. While the government of Lt. Col. Mengistu Haile Mariam insists resettlement is the only possible long-term solution to chronic famine in the highlands, western donors see less altruistic motives.

The United States, by far the largest food donor, is the most outspoken critic of the mass movement of peasants to the south. "Resettlement is a diversion of resources that could be better spent if used for people directly," M. Peter McPherson, director of the U.S. Agency for International Development, said in Washington last week.

The Heritage Foundation, an influential conservative think tank, said resettlement is "prompted by political, not humanitarian, considerations. By depopulating the rebel-dominated northern highlands, the Mengistu regime hopes to drain the ocean in which its guerrilla opponents swim."

In any case, in the north there is next to nothing for anyone -- guerrilla or not -- to eat. Foreign agricultural specialists here say the drought-seared land has been ruined, probably for decades, by deforestation, erosion, overpopulation and destructive farm practices. There is no way, these specialists say, that the highlands can feed the 7 million or so people who now live there.

Further, at least half of the 1.5 million peasants scheduled to be relocated live not in northern Tigray Province, where the Tigray People's Liberation Front claims control of 85 percent of the province, but rather in Welo and Gondar provinces, where rebels are not a significant threat to the government.

The resettlement is not to touch Eritrea, the most northern Ethiopian province, where rebels of the Eritrean People's Liberation Front are the strongest threat to the government.

Resettlement appears already to be a fait accompli. The Ethiopian government has proclaimed resettlement as its most important priority, and, with the help of 12 Soviet-built Antonov cargo aircraft and more than 300 Soviet-built trucks, about 20,000 peasants are moving south each week.

"Whether the world likes it or not," said the Australian diplomat who has seen the resettlement areas, "there are already more than 120,000 people who have been resettled and who, with a minimum of assistance, could rehabilitate themselves."

"The question now is not whether resettlement is good or bad," said Alan Court, a senior official in Addis Ababa for the United Nations Children's Fund (UNICEF). "It has happened. The question is, do you sit back and say you Marxists have not done enough preparatory work or do you help them?"

Among representatives of such midsized donor countries as Australia, Canada, Sweden and Italy, there is a consensus that the United States has been too quick to denounce resettlement, condemning it as a Soviet-inspired scheme without considering that it could help solve some of Ethiopia's long-term problems.

"I would say that the United States, as far as resettlement is concerned, is more worried about East-West relations than it is about starvation," said a senior Canadian diplomat.

Angrily charging that "the role of beggar suits no man well, least of all the laboring Ethiopian," the government here demanded last month that the West support resettlement with "a vastly increased flow of funds."

Ethiopia wants donations of machinery to clear land, oxen and hand tools for the destitute settlers, seeds, pesticides, fertilizers, fuel, well-drilling machinery, 300,000 sets of kitchen utensils and clothing.

In its rhetoric, at least, the government does not seem to be underestimating the difficulty of moving millions of peasants from temperate highlands to malarial lowlands that never before have been cultivated.

"Settlement projects are indeed difficult," said a recent government document. "They require meticulous coordination. Moreover, settlement involves the crossing of physical, socioeconomic, psychological and emotional barriers. This means . . . the total transformation of the life style of the settlers."

Without the massive aid that the government has demanded, Ethiopia seems too poor to afford what will be the largest public works project in the 10 years since the military seized power.

Indonesia, which operates a similarly ambitious program to relocate about 2.5 million peasants over five years from the overcrowded island of Java to less populated islands, spends about $5,000 per family, according to the World Bank. The money buys the settlers a house and farm tools, builds roads and health clinics, and provides support for a year.

Ethiopia's annual cost for a similar program is estimated at $1.5 billion -- about double the government's annual budget.

Not only does the government seem unable to afford the long-term costs of a well-managed resettlement, but foreign medical experts here say it is incapable of dealing with the immediate medical problems created when hundreds of thousands of malnourished highland peasants are moved suddenly to tropical lowlands.

"They don't have enough doctors and medical facilities to take care of malaria," said Dr. Fabrizio Bassani, an expert on refugee medicine with the Italian Embassy.

Bassani said there is no precedent of primitive people quickly learning to take the pills that could protect them from malaria. He also said the government has not shown that it is treating the health problems of highlands peasants -- pneumonia, diarrhea, measles, tuberculosis, leprosy -- before it moves them south.

"When they move these people together, they bring all their medical problems with them," Bassani said. "I think it is a very critical situation. The government gives no clear explication of how the medical problems will be handled."

Medical problems, however severe, are a secondary worry in Ethiopia, according to Alan Court of UNICEF, who says the West has no choice but to support resettlement.

"The prime medical problem in this country is not malaria or TB or leprosy. It is lack of food. The peasants who are being moved to the south are being fed -- the government is making sure of that. And they will soon be able to grow their own food," Court said.

Any assessment of how the resettlement is going is likely to take several months.

Thus far, the government has restricted outside access to the newly settled areas, allowing brief guided tours by outside delegations -- such as representatives of the Australian government and the U.N. Food and Agriculture Organization -- that it apparently believes are predisposed to support the program.

The government claims it is moving only those peasants who volunteer, that it is keeping families together, and that it is giving each family about five acres of land. Reports from diplomats in Addis Ababa who have seen the resettlement areas support these claims.

Farmers in the new areas will be allowed to grow what they want on their parcels of land and will be able to keep all of their profits, according to Tamrat Kebede, a chief planner. But, Kebede said, they will not own the land and, in time, all the resettlement farms will join in "producers' cooperatives" with shared production and shared profits.

Over the past five years, according to western economists, all the state-owned farms and producers' cooperatives in Ethiopia -- which account for about one-tenth of the country's farm production -- have lost money.

Kebede would not say how quickly the resettlement farms would be collectivized. "We will leave it to its own historical process," he said.

Unless it can persuade western donors that communist-style farming is indeed only in the very distant future for the resettlement areas, the Ethiopian government appears to have painted itself into a corner.

It desperately needs outside help to make the resettlement work, but its plans to collectivize the new farms, turning them into proven money-losers, seem likely to keep out western money and technical help.

Asked about his government's dilemma, Kebede said that Ethiopia wants humanitarian aid from the West, not policy advice.

"We are a proud country. In the feeding camps you will see no grabbing of bread, no looting. People die proud," Kebede said. "I find it offending that this pride would be manipulated by the West for political purposes."