During a five-year-long stretch as a member of Ugandan President Idi Amin's Cabinet, Henry Kyemba enjoyed the privileges of rank without having authority. The way he puts it, he was forced to be minister of health.

"It is a job you can't resign from," he said in an interview. "If you do, it would mean you were opposed to Amin's policies and he would have you killed."

In fact, he said, six Uganda Cabinet ministers were murdered while 15 others have fled the country since Amin took power in 1971 military coup.

In May Kyemba defected as well, managing to take his two wives and two children to London. This week he was in Washington to promote his book on the murderous anatomy of Amin's rule.

Kyemba's American publisher, Ace Books of New York, has printed half a million copies, and is trying to generate publicity for Kyemba to promote sales. Kyemba, on the other hand, is trying to generate opposition to the Amin regime among U.S. policymaker.

So far, his trip has brought mild disappointments. The two men who have publicly denounced the Amin regime and whose voices were heard throughout Africa wre "too busy" to see the Ugandan exile.

The two are Sen. Daniel Patrick Moynihan (D-N.Y.), former U.S. ambassador to the United Nations, and the present ambassador, Andrew Young. Kyemba had hoped to enlist their support and strengthen the cause of a growing number of anti-Amin Ugandan exiles.

At 38, Kyemba is a trim, handsome and articulate man who believes that blacks - rathan than whites - should speak out against Amin and his reign of terror. His book, "A State of Blood," is loaded with gruesome details of killings in Uganda. By Kyemba's account, at least 150,000 Ugandans have been murdered by Amin's security forces. As minister of health, Kyemba was well placed to make such estimates.

Yet the enormity of the horrors Amin has inflicted on his country have long been ignored by the international community while his erratic behaviour toward other countries and violence against Western residents of Uganda have received wide attention. Kyemba is trying to make Amin's crimes an international issue.

"It is a said situation when the world reacts only if a white man is killed," he said sadly. "Human life - black or white - is human life.

"I want to disclose the truth about Uganda, I am not interested in money."

How much money did he receive from Ace Books? The publisher had earlier refused to disclose the amount, and a publisher's representative advised Kyemba not to discuss money. "I can tell you," Kyemba volunteers, however, "that I do not own the copyright on my book."

The copyright is held by Paddington Press Ltd., of London. Both Paddington and Ace are expected to make a solid profit capitalizing on the current interest in Uganda, and the book is a delight for those with the stomach to read about Amin's canibalism, massacres, dismemberment of bodies and the like.

Kyemba also provides evidence of Amin's complicity and cooperation with the terrorist hijackers of an Air France jetliner resulting in the Israeli raid on Entebbe Airport.

Kyemba, who has held high government jobs ever since he graduated from college in 1962, said Amin's rule has weakened the country economically while promoting lawlessness and corruption. "He cannot last very long," he said. He and his fellow exiles are now trying to develop a plan to speed up Amin's collapse.

"I am not looking for a permanent job abroad," Kyemba said, laughing. "We'll be home soon."