NAIROBI, KENYA, FEB. 11 -- Ethiopian soldiers killed at least 20 civilians and wounded about 20 others early this week when a group of famine victims refused to board trucks bound for a government resettlement site, according to sources in the Ethiopian capital, Addis Ababa.

The incident has alarmed western aid donors there who are rushing to transport more than 1 million tons of food to an estimated 7 million Ethiopian drought victims.

The shooting also has raised angry questions among donors about the apparent resumption of forced resettlement. The Ethiopian government suspended its resettlement plan two years ago, admitting that there had been ill-treatment of famine victims by "overzealous officials." Resettlement resumed late last year with governmental promises that it would be strictly voluntary.

According to reliable sources reached by phone in Addis Ababa tonight, troops rounded up for resettlement about 3,000 people near Korem in the central highlands last Sunday. The town is a major food distribution center, where bags of grain are handed out to about 12,000 drought-affected families who walk in from the surrounding hills.

The sources said the soldiers, in making their selections, appeared to single out peasants from Tigray, a nearby region controlled by rebels of the Tigray People's Liberation Front. The rebels oppose resettlement, which transports farmers from the northern highlands to fertile regions in the southwest corner of the country. Rebel policy is to press peasants not to volunteer.

Those rounded up Sunday were kept overnight in a large shed and on Monday morning were ordered to board 17 trucks, the sources said. When the people refused to move, the sources said the soldiers opened fire.

"After they shot into the crowd, the people did board the trucks," said one source. He said the trucks headed south, apparently toward the resettlement transit center at Harbo in Wello region.

Ethiopian government officials could not be reached for comment tonight on the incident, which has prompted Michael J. Priestly, head of the U.N. Emergency Operation in Ethiopia, to demand an official explanation.

Sources say Priestly, who refused comment tonight, had scheduled an urgent meeting for this afternoon with Berhanu Jembere, head of Ethiopia's Relief and Rehabilitation Commission. But the meeting was canceled, sources said, when Berhanu was called to a meeting with his superiors.

"This whole thing could have been one of these local guys who just got carried away with his orders," said an experienced relief official in Addis Ababa. According to this official, governmental directives recently have gone out to local administrators to speed up the movement of settlers. "They have been told to use force if they have to," the relief official said.

Since November, when the resettlement program resumed, an estimated 6,000 to 7,000 people have been transported south. Most were from the west-central Gondar region, not severely affected by rebel fighting. Peasants from Gondar volunteered to resettle, officials say.

The Ethiopian government, with the backing of several private western relief agencies and aid money from the Italian government, has pushed resettlement as the only sound alternative for farmers living in the overcrowded, environmentally ravaged and drought-prone central highlands.

The program began in late 1984, at the height of the severe famine, and moved about 600,000 people to sparsely populated land in the southwest of the country.

While there was widespread western criticism of the treatment of many of the settlers, reports by several respected relief agencies say that some of the resettlement areas have achieved or are nearing self-sufficiency in food production.

In interviews, a number who fled into bordering Sudan said they were tricked by promises of free food and forced onto resettlement trucks. Others said they were beaten by soldiers and that members of their families were shot at resettlement sites.

The Ethiopian government this week prevented a U.N. field officer, who normally has access to the feeding operation at Korem, from going to the scene of the reported shooting. Teams from CBS News and National Public Radio, which are in the Ethiopian capital and which had been scheduled to go to Korem, have been prevented from doing so.

In the 1984-85 famine, Korem was a highly publicized famine camp with as many as 100,000 residents. Thousands of famine victims died there, mostly from infectious disease spread by overcrowding and unsanitary conditions.