MEXICO CITY — While the world awaits findings from new AIDS prevention trials, millions of people are becoming infected because governments are overlooking studies showing that behavior modification works, AIDS experts said Tuesday.

Among the behavior modifications the experts cited: promoting safer sex through delayed intercourse and the use of condoms, decreasing drug abuse, providing access to needle exchange programs and promoting male circumcision.

But none of the measures alone offers a simple solution to preventing infection with HIV, the virus that causes AIDS, the experts said in a number of reports and news conferences at the 17th International AIDS Conference here.

The experts said characteristics of the global epidemic varied greatly among and within countries, most of which are not focusing prevention resources where their epidemics are concentrated. Combining these measures and delivering them on a wider scale is crucial to reversing the global HIV epidemic, they said.

Health workers have had initial successes in providing antiretroviral drugs to treat an estimated 3 million people worldwide. But tens of millions more people need the drugs, and additional millions are now becoming infected.

The world cannot treat its way out of the AIDS epidemic, many experts have long said, and a scientific debate exists over the extent to which antiretroviral therapy can reduce transmission of the virus. A pressing need exists to combine HIV prevention and treatment efforts, experts said Tuesday.

Researchers involved in each field "need to get married today," said Dr. Myron S. Cohen of the University of North Carolina. "We need to be one community."

A 50-member panel known as the Global HIV Prevention Working Group, which is supported by the Bill & Melinda Gates Foundation, released a report saying that prevention efforts must address a number of perception problems.

One is misplaced pessimism about the effectiveness of prevention strategies. A second is confusing the difficulty in changing human behavior with an inability to do so. A third is a misperception that because it is inherently difficult to measure prevention success, those efforts have no impact, the report said.