Drought in eastern Ethiopia has destroyed a 2 1/2-year-old, $21 million United Nations effort to resolve one of the world's largest and longest-running refugee problems, a U.N. official said here last week.

For much of the past seven years, since the 1977-78 Ethiopian-Somali war ravaged vast tracts of the disputed Ogaden Desert, more than a million Ethiopian nomads have lived as refugees in Somalia and nearby Djibouti.

The Office of the United Nations High Commissioner for Refugees had managed to repatriate 350,000 of these nomads to Ethiopia voluntarily, luring them back from refugee camps to their ancient homeland with gifts of food, blankets, soap, hoes, axes and, most importantly for the pastoral nomads, livestock. The nomads were given 40,796 head of cattle, sheep and goats.

Now, according to Colin Mitchell, who helped design the repatriation plan for the United Nation's refugee office, drought has killed half the nomads' donated cattle and livestock, about 30 percent of their children are severely malnourished and tens of thousands of nomads -- driven by hunger -- are walking back to Somalia and Djibouti.

"The drought is destroying all our work," said Mitchell, who has just returned to Addis Ababa from the Ogaden. "We run the risk that all these people who have come back to Ethiopia will turn around and go back to where help is available -- Somalia and Djibouti."

Reliable reports indicate that 50,000 refugees already have moved back to Somalia and 10,000 more have returned to Djibouti. In Somalia alone, the cost for international donors to maintain Ethiopian refugees in 35 camps has been running at more than $30 million a year, Mitchell said.

The drought-triggered marches of these "economic refugees," 80 percent of whom are women and children, are only part of what Mitchell terms a "predisaster" that has developed in Harerge Province, a 156,000-square-mile region that forms the eastern corner of Ethiopia.

There are more than 900,000 people in Harerge who are said by relief officials here to be threatened by the drought. This is more than twice the number of people estimated to be threatened just two months ago. Grain stocks in Harerge "are absolutely negligible," according to Mitchell, the second-ranking official of the United Nations High Commissioner for Refugees' office in Ethiopia.

As in neighboring Shewa Province, where drought has only recently begun to turn to famine and where 4,000 peasants have died since August, Harerge has not yet developed food aid supply links with the government's Relief and Rehabilitation Commission or with private international relief agencies.

In the next year, Mitchell estimates that the province -- home to nomadic and seminomadic clans known as Issa-Somalis -- will need about 164,000 tons of food. Thus far, donations targeted for Harerge include just 7,000 tons from the European Community and a possible pledge of 15,000 tons from Canada.

"By January and February, without large quantities of food and drinking water for people and their animals, we are going to have a famine on no less a scale in Welo and Tigray," Mitchell said.

Five million people are said by the government to be affected by famine in those two Ethiopian north-central highlands provinces where most of the more than 300,000 famine-caused deaths have occurred in the past nine months.

Of the estimated 10 million refugees in the world, the U.N. high commissioner's office says one-third are in Africa. Of these 3.3 million African refugees, one-third are the Issa-Somali nomads who were chased off their traditional pasture land by the Ethiopian-Somali war.

Before severe drought struck this year in the Ogaden, scorching most of the region's grazing land, the U.N. refugee office had planned to continue to use the "pull factor" of free animals to induce many of the 700,000 nomads still living in Somali relief camps to come home. The approach was sanctioned by a rare agreement between Ethiopia and Somalia, which continued to support rebel groups aimed at overthrowing each other's governments.

Mitchell said that U.N. refugee officials scoured southern Ethiopia to buy livestock. Once purchased at a cost exhausting most of the $21.2 million repatriation program's budget, the 40,796 goats, cattle and sheep were trucked hundreds of miles from Sidamo and Bale provinces to the Ogaden.

Mitchell said the livestock were given to nomads who were eager to resume their seasonal wanderings with the animals.

"We gave them the animals, then we got screwed by the drought," Mitchell said. "Well over 50 percent of the animals have perished."

Mitchell has written off the refugee rehabilitation program as a "failure," but he says the issue in Harerge is now far more serious than the demise of a multibillion-dollar U.N. program.

"It is one thing to have limited success in rehabilitating refugees," he said, "but it is quite another to have to sit back and watch people die."