In August, the last time terrorists blew up a passenger bus, Jerusalem's blood bank put out an urgent appeal to help the wounded. Uri Tamiat set aside his plans and waited in line to donate a pint at the bloodmobile outside the Mashbir department store.

Tamiat, 25, believed he was contributing in the most personal way to a fellow Israeli in need. But when he stepped off the stretcher and departed the van, Tamiat realized today, a technician took the young man's blood and set it aside as infectious waste.

Israel acknowledged today that it has been the government's secret policy for years to discard the blood donations of Ethiopian immigrants for fear of AIDS. Revelation of the policy brought one more jolt of humiliation to a community of dark-skinned African Jews still struggling for acceptance after its dramatic airlift here beginning 12 years ago.

"It's one of the most degrading things I've ever experienced," Tamiat said in an interview today. "I thought they were saving somebody, giving a transfusion to somebody. They lied to me, and they took my blood and poured it into the garbage."

Two sensational airlifts, Operations Moses and Solomon, brought some 21,000 distressed Jews from Ethiopia in 1984 and 1991 -- two-thirds of them in a single weekend that stands as one of the world's remarkable feats of covert logistics. But now Israel's Ethiopian community, grown to 50,000, feels itself sinking into an underclass.

A recent education study showed that needlessly large numbers of Ethiopian elementary schoolchildren are channeled into classes for the learning disabled, and teenage Ethiopians are largely schooled in vocational tracks that prepare them for some of society's least rewarding jobs. A majority of Ethiopians are housed in grim trailer parks in distant "development towns," and their religious leaders are not recognized by Israel's government-sponsored rabbinate.

Some of the community's problems have mirrored those of other large waves of immigrants, from Morocco and Iraq in the 1950s and, more recently, from the former Soviet Union. And many Israelis sincerely admire the ability of the Ethiopian Jews to maintain their faith for centuries of isolation from Jewry elsewhere.

But commentators increasingly see the specter of racism in Israel's treatment of its darkest-skinned Jews, and today's disclosure in the newspaper Maariv appeared to strike a nerve. Though carried only in one newspaper, and buried on an inside page at that, the blood scandal was the hottest topic on the morning radio shows.

"Is their blood the same as our blood?" asked Micha Odenheimer, director of the Israel Association for Ethiopian Jews. "We say we've accepted them into our society as Jews. Have we really?"

Government officials were forced to confirm the story after Maariv published a photograph of a bag of blood with this handwritten notation on its tag: "Do not use because he is from Ethiopia."

Zvi Ben Yishai, the deputy director of Haifa's Rambam Hospital and chairman of the government-run National AIDS Committee, defended the policy in an interview as "justified for the protection of the public," because, he said, Ethiopian immigrants have as much as 50 times the incidence of AIDS as other Israelis.

"Of course the authorities are against any form of discrimination," he said, in remarks backed by Health Minister Ephraim Sneh. "One has to understand, though, that from the public health point of view, one has to make sure nobody is going to get in a hospital after a road accident and receive a transfusion of blood that might be contaminated."

But Yoram Lass, a member of Israel's parliament and former director general of the Health Ministry, described the screening policy as "racist and unfounded scientifically." Americans, he said, have a much higher rate of AIDS infection than Israelis, but Israel would never contemplate banning donations from American Jews.

"You cannot insult people and deceive people by taking blood from their veins and then discard it as trash," he said. "You simply cannot do it."

Israeli health officials, defending themselves, today cited the American practice of barring Haitian immigrants from donating blood.

Beginning in 1983, Haitians entering the United States were prohibited from donating blood because of inexplicably high rates of AIDS among them. The ban was lifted in 1990 when more was known about transmission of human immunodeficiency virus (HIV), which causes AIDS, and epidemiologists determined they could eliminate virtually all infected blood donations by asking donors explicit questions about their sex and drug-use habits.

In 1988, recent emigrants from sub-Saharan Africa were banned from giving blood after a rare virus, called human immunodeficiency virus type 2 (HIV-2) was found in that region. That ban was lifted in 1992 when a test for HIV-2 was developed.

Such AIDS tests are also used on every blood donation here. They are not perfect, however, since there is a period of roughly 25 days after infection during which the virus cannot be detected. It was apparently in an effort to eliminate that slim chance of contamination that the Ethiopians' blood was rejected. Already alienated and distraught, however, many Ethiopians perceived the blood ban as a powerful symbol of Israel's view of them.

Tamiat, who directs a center for Ethiopian teenagers in Tel Aviv, said he had no good answer for his students when "they said to me, All the time you try to tell us to be Israelis and integrate into Israel, and here again we see . . . they don't even see us as human beings.'"

"This is pure racism," Adiso Masala, head of the Organization of Ethiopian Immigrants, told Israeli army radio in an interview relayed by the Reuter news agency. "We are blood brothers with the Israelis but our blood is thrown in the garbage because we are black."

Benny Mekonnen, a 30-year-old reserve paratroop officer, was so distraught that he could hardly speak when a reporter interviewed him today. Mekonnen, who attended a university in Denmark and married a woman from there, said he was more certain now than ever there is no place for Ethiopians in Israel.

"I'm very, very angry now, so you would maybe think I'm very extreme, but this article in the newspaper almost killed me," he said. "I give blood every year, once a year. They took our blood and threw it in the garbage. I just don't know what to say. I'm just feeling that I want to leave this country forever. My wife is from Denmark and I have the possibility to leave this country, and I'm going to do it." Staff writer David Brown in Washington contributed to this report.