Current estimates for the number of people in India with the HIV/Aids figures could be greatly exaggerated, a leading Aids worker says.
India has more HIV infections than any other country, the UN says
The UN says 5.7 million people in India have the HIV virus, the highest number in the world.
But Ashok Alexander, of the anti-Aids Avahan organisation says figures due out soon could be "substantially lower", the Associated Press reports.
The BBC has learned that the figure could be as low as three million.
Experts say that the discrepancy between 5.7 million and three million could only be explained by errors in the methods of calculating the numbers of people with the HIV virus.
India is about to embark on a new and expanded phase of its Aids control programme, with increased funding from the government and from international donors.
"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 programme of the Bill and Melinda Gates Foundation, said, the Associated Press news agency reports.
Officials say the virus is spreading to low-risk groups
Mr Alexander said the new estimates were likely to be more accurate because they came from pre-natal clinics, high risk groups and from the government's National Family Health Survey.
He said that this was a far more accurate way of collating the figures than previous estimates which only relied on details provided by pre-natal clinics.
Mr Alexander declined to speculate on what the new total would be, pointing out that data is still being assessed and exact details will not be available for a few more weeks.
Last week, India health officials said they were alarmed by the growing numbers of pregnant women infected with HIV/Aids in the northern states of Uttar Pradesh (UP) and Bihar.
They are among India's most backward, with huge populations but poor literacy and health services.
Officials say workers who migrate to cities in search of work bring the infection back to the states with them.
They said that unless the state governments got serious about tackling the disease, there could be an Aids epidemic.