Methods used to estimate the number of people affected by HIV/Aids in India are flawed and the actual number of cases may be lower, a new study says.
The UN estimates that India has the highest number of HIV infections with 5.7 million people with the virus.
The study in British journal BMC Medicine says the number of people with the infection may be only 40% of the official estimate.
The UN said it was too early to say if the data applied to India as a whole.
Recently, former US President Bill Clinton called India the epicentre of the global HIV/Aids epidemic.
The study is based on research in one district in the southern Indian state of Andhra Pradesh, which is worst-hit by the infection.
Investigators collected blood samples from 12,617 people aged between 15 and 49 years in Guntur district - one of the worst affected areas in the state - to come to their conclusions.
The method estimated that there were 45,900 people living with HIV in Guntur, compared to the estimate of 112,600 reached by the official method.
Extrapolating its findings, the study believes that there may be between 3.2 million and 3.5 million adults with the infection in India.
"India may be overestimating its HIV burden with the currently used official estimation method," the study said.
However, study investigator Dr Lalit Dandona said that even though his team's numbers were smaller, they were "by no means suggesting that the problem is already taken care of".
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