London: The number of people living with HIV in India could be lower than government estimates, research issued on Wednesday said.

Scientists who studied the prevalence of the virus that causes AIDS in a district in Andhra Pradesh (the state has the highest HIV rate in India), found it was less than half the government's figure.

Instead of 112,600 HIV cases in the district of Guntur, Lalit Dandona, of the Administrative Staff College of India, in Hyderabad estimates the number is about 45,900. "The official method in India leads to a gross over-estimation of the HIV burden in this district," Dandona said in a report published in the journal BMC Medicine.

"The potential major implications of these findings for the overall HIV estimate for India need to be examined," he said. The United Nations estimates India has the largest number of people living with HIV/AIDS at 5.7 million.

The researchers tested blood samples from more than 12,000 men and women aged 15-49 from both urban and rural areas in Guntur who were representative for the study.

The HIV prevalence rate they found was 1.72 percent and rose to 1.79 percent, or 45,900 cases, after they adjusted the number for high risk groups.

Official figures based on data collected from antenatal clinics, sexual health clinics, high risk groups and referrals of HIV positive and suspected cases to public hospitals put the number of cases at 112,600.

Dandona said public hospitals have disproportionately high rates of HIV because they are used more by patients from lower socio-economic groups who have a higher prevalence of HIV.