Some 700 people are infected with HIV every day, but the annual infection rate could be slashed by two thirds, the director of UNAIDS Peter Piot and his colleagues said in a statement at the 17th International AIDS Conference in Mexico City, also published in the British medical weekly The Lancet.
UNAIDS estimates that HIV prevention will cost 11.6 billion dollars by 2010 and 15.3 billion by 2015 as programs move towards universal access.
HIV prevention often takes a back seat in the war against AIDS, behind advances in antiretroviral drugs which keep millions alive.
But combined prevention -- including condoms, circumcision, needle exchange, and changes in sexual behavior -- has gained ground in discussions at the Mexico meeting, which ends Friday.
"Governments, communities and scientists must fully implement combination HIV prevention, and the international community must mobilize all the support necessary for this effort," said UNAIDS officials.
They said that the most important HIV prevention programs in the field lacked money and did not target the most needy.
"International institutions, national governments, and community activists must work together to build demand for HIV prevention," the statement said, adding that "none of the successes in HIV prevention over the past quarter of a century have been easily won."
UNAIDS officials also urged the pursuit of an HIV vaccine, despite recent setbacks, and called for investment in research for potential HIV-prevention technologies.
Last year, 2.7 million people became infected with HIV, bringing the global total to 33 million.