KENNEBUNKPORT — President Bush signed an $882 million AIDS emergency bill Saturday that for the first time will allow direct federal grants to 16 cities hit hardest by the deadly viral epidemic.

Bush affixed his signature without public comment to the Ryan White Comprehensive AIDS Resources Emergency Act, named for the Indiana teen-ager widely admired for his courage in face of the disease that claimed his life in April.

Congress will still have to pass a separate appropriations bill before any of the funds are distributed to states and cities. But it is the first law ever enacted to provide health grants to states and localities to fight a specific disease.

AIDS is spread through the exchange of blood or body fluids or through contaminated needles. It has killed more than 83,000 Americans in the last decade, and an estimated 1.5 million Americans are believed to be carriers of the virus.

Many of the victims have been homosexual or intravenous drug abusers. Children can contract the disease in the womb or through blood transfusions, as did Ryan White, a hemophiliac.

The measure authorizes $882 million for fiscal 1991 and a total of $4.5 billion over five years.

It would provide $275 million in health care service grants in fiscal 1991, which starts Oct. 1, to 16 major cities.

To qualify, a city had to have at least 2,000 AIDS cases to date or a rate of 25 per 10,000 residents. The money will be allocated based on severity of need.

States would also get formula grants to improve the delivery of health care services for people with AIDS. There would be separate grants to states and health care organizations for AIDS prevention efforts.