WASHINGTON » Federal health regulators have delayed a decision on whether to approve the first pill shown to prevent HIV infection, the drug’s manufacturer says.

Gilead Sciences disclosed Friday that the Food and Drug Administration will take three more months to review its application for Truvada, after the company submitted additional materials to the agency earlier this month.

In May, a panel of experts recommended approval of the daily pill for healthy people who are at high risk of contracting HIV, including gay and bisexual men. The vote was nonbinding, though the FDA often follows the group’s advice.

Gilead said it submitted updated information on its planned safety materials for patients and doctors using the drug. The FDA typically extends its reviews after receiving such information.

The FDA is now expected to rule by Sept. 14, the company said in a statement.

Gilead Sciences Inc., based in Foster City, Calif., has marketed Truvada since 2004 as a treatment for people who are infected with the virus. The medication is a combination of two older HIV drugs, Emtriva and Viread.

Truvada made headlines in 2010, when government researchers showed it could actually prevent people from contracting HIV when used as a precautionary measure. A three-year study found that daily doses cut the risk of infection in healthy gay and bisexual men by 42 percent, when accompanied by condoms and counseling. Last year another study found that Truvada reduced infection by 75 percent in heterosexual couples in which one partner was infected with HIV and the other was not.

An estimated 1.2 million Americans have HIV, which develops into AIDS unless treated with antiviral drugs. AIDS causes the body’s immune system to break down, leading to infections which are eventually fatal. Gay and bisexual men account for the majority of cases — nearly two-thirds.

Because Truvada is on the market to manage HIV, some doctors already prescribe it as a preventive measure. FDA approval would allow Gilead Sciences to formally market its drug for that use.

But Truvada’s groundbreaking preventive ability has exposed stark disagreements on prevention among those in the HIV community. While Truvada’s supporters say the drug is an important new option to stop the spread of AIDS, critics worry that the drug could give users a false sense of security and encourage risky behavior.

Groups including the AIDS Healthcare Foundation have asked the FDA to reject the new indication, saying it could reduce use of condoms, the most consistently reliable prevention against HIV.

The number of new HIV infections in the U.S. has held steady for 15 years at about 50,000 per year. With no vaccine in sight and an estimated 240,000 HIV carriers unaware of their status, most doctors and patients say new methods are needed to fight the spread of the virus.