The nation's largest group of doctors says physicians, as a last resort, must breach their centuries-old tradition of confidentiality by warning the sexual partners of those infected with the AIDS virus.

The move during Thursday's final session of the American Medical Association convention was part of a package of tough policies for battling the AIDS epidemic, including calls for mandatory testing of prison inmates and expanded programs for intravenous drug users.

"This is a landmark in the history of medical ethics," said Dr. James E. Davis, the new president of the AMA.