India has far fewer HIV/AIDS cases than previously believed, according to new data from a comprehensive national study.

Experts say the still-unreleased survey is likely to show a significant drop in the number of cases from last year's U.N. estimate of 5.7 million, which pushed India ahead of AIDS-ravaged South Africa as the country with the world's highest number of cases.

"The actual number we've come up with in aggregate is likely to be lower, and perhaps substantially lower," Ashok Alexander, director of Avahan, the Indian program of the Bill & Melinda Gates Foundation, which helped fund the study, said Friday.

Alexander declined to offer any estimates of what the new total would be, saying the data is still being analyzed and precise numbers won't be released for a few more weeks.

The new estimate comes from combining data collected from prenatal clinics, a survey of high risk groups, such as sex workers, and from the government's National Family Health Survey — a method Alexander said was more reliable than the previous estimates, which simply relied on extrapolating from the prenatal clinic data.

The health survey — the third conducted since 1992-1993 but the first to provide an HIV estimate — is considered the most comprehensive source and carries the most weight in determining the new figures. It covers about 200,000 people between the ages of 15 and 54, more than half of them women, and was conducted through face-to-face interviews all across India between December 2005 and August 2006. It has no significant margin of error.

While health experts called the new data good news, they cautioned that AIDS is still a major problem in India, particularly in southern states where HIV rates might be as high as 1 percent of the general population.

"This is a bit like declaring victory before even fully fighting the battle," Alexander said.

The disease continues to be most prevalent among India's high-risk communities: sex workers, men who have sex with men, truckers, and intravenous drug users.