An international controversy has arisen over whether American health officials have unfairly categorized residents of Haiti and Haitians in the United States as having an increased risk of contracting acquired immune deficiency syndrome, or AIDS, a fatal and thus far incurable disease.

Haitian medical experts say United States Public Health Service officials made a serious mistake, and assert that researchers used faulty and sometimes prejudiced methods. But American Government health officials defend their research methods and insist their categorization is correct.

In the United States, in addition to Haitians, others regarded as being in the AIDS high-risk group are male homosexuals, intravenous drug users, hemophiliacs and, in a much lower number of cases, recipients of blood transfusions. New York City officials have removed Haitian-Americans from that list, saying the number of cases is too small to justify their inclusion and that many Haitian AIDS victims appear to be members of the other high-risk groups.

More Than a Medical Impact

Haitians say the effect of being placed in the risk group goes beyond the medical implications and has had an adverse impact on many aspects of their social, cultural and economic life both here and in Haiti.

To get behind the dispute and its origins, The New York Times reviewed recent medical findings and statistics about the immunedeficiency disease and held several interviews with American health officials and academic researchers, as well as with Haitians and Haitian-Americans.

The Haitian medical leaders' basic criticisms of the American action were listed by Dr. Saidel Laine, president of the Haitian Medical Association. He said American health officials had used unscientific methods in their investigations, which he called ''racist,'' and said the findings had left a whole nation of people unduly alarmed and unfairly stigmatized.

The American officials, while conceding that more information about the disease was needed and that it had been extremely difficult for Haitians to accept the designation as an AIDS risk group, said the classification remained not only valid but also critically important. Higher Rate for Haitians

Statistics gathered so far, Federal epidemiologists say, show the rate of AIDS diagnosed in this country among Haitian-born people to be at least ten times higher than the rate for all Americans. Because of that, they say, all Haitians must be considered by the medical authorities to have an increased chance of getting the disease and must themselves acknowledge this higher risk. The rates for AIDS in Haiti are unknown.

These other developments were disclosed in the interviews and review of existing studies:

- Haitians in the United States say that because they have been labeled as carriers of a deadly disease, they have also become victims of a new outbreak of social discrimination among people with unwarranted fears that they can contract the disease through routine social contact. Evidence to date suggests AIDS is transmitted through intimate sexual contact or through contaminated blood. Alex Remponeau, a spokesman for an international group formed by Haitian-Americans to study the problem, said Haitians had been forced to take leaves from their jobs and had been unable to sell their houses. And a New York AIDS task force, in a report to Governor Cuomo, expressed concern about Haitian-American civil rights, saying, in part, ''Haitians are being fired from their jobs for no reason other than their national origin.''

- Haiti, which shares the Caribbean island of Hispanola with the Dominican Republic, has had a drop in tourism of about 20 percent from last year, according to the Haitian Government. Tourism is one of Haiti's chief industries.

- Doctors in Haiti have reversed themselves and are now acknowledging that there are a number of homosexuals in that country. Only a few months ago they insisted homosexuality was taboo and therefore uncommon, according to American doctors who visited the country to investigate AIDS.

- Haitians, angered about reports in American medical journals suggesting that the disease was exported from Haiti to the United States, have countercharged that it originated in the United States and was taken to Haiti by homosexual tourists who transmitted the disease to male Haitian prostitutes.

- Federal health officials have stepped up their research into the Haitian-AIDS link, saying it may offer important clues to the mysteries of what many health experts regard as one of the most frightening epidemics in recent decades.

- Medical researchers in Haiti have intensified their own investigations. Charges of Racism

The charges of racism against American health officials are said to have been made first at a recent meeting of the Haitian Medical Association in Port-au-Prince. The association and three groups of researchers now working on the disease in Haiti challeged the classification issued by the Centers for Disease Control in Atlanta, saying in a statement, ''This unscientific and racist attitude only refelects the inability of the C.D.C. to define high-risk groups in the Haitian population.''