A government-sponsored study of two measles vaccines, begun in 1989 during a major U.S. epidemic and conducted on nearly 1,500 minority infants in Los Angeles, failed to disclose to parents that one of the vaccines was experimental, federal health officials said yesterday.

"A mistake was made," said David Satcher, director of the Atlanta-based federal Centers for Disease Control and Prevention, one of the study's sponsors. "It shocked me."

Satcher said in an interview that the CDC plans to contact all the families involved, and said he was very concerned that the events not fuel suspicion in the minority community of government medical research.

"Every little mistake like that seeds the concerns of people," he said. "We need to move to a new level of assurance so people can really trust what we're doing."

None of the Los Angeles children, most of whom are now 5, was injured by the unlicensed vaccine, the CDC said. However, similar clinical trials conducted in Africa and Haiti with the vaccine raised questions about its relationship to an increased death rate among female infants who received the more potent of two dosages. For this reason, the Los Angeles study was halted in 1991.

The inquiry into the measles research was conducted after a physician connected to a public interest vaccine safety group raised questions. Satcher, who was not CDC director at the time the study began, said he concluded from his review that "there was no ill intent" on the part of the agency by not telling parents that the vaccine had not been licensed for use in the United States.

CDC officials acknowledged that the omission was serious and attributed it to researchers' knowledge that the lesser doses of the unlicensed vaccine, known as Edmonston-Zagreb, or E-Z, had been used safely for decades outside the United States, and that it was recommended by the World Health Organization.

The study was co-sponsored by Kaiser Permanente of California, and was begun during a national measles epidemic that struck California particularly hard.

The purpose was to compare E-Z with the Moraten vaccine, the standard vaccine used in this country. Researchers were trying to determine whether immunity could be obtained by vaccinating children younger than 1 year old, and which of the dosage strengths should be used.

The majority of the children were black and Latino and lived in lower-income neighborhoods in and near Los Angeles.