By Geeta Pandey
BBC News, Delhi
The Indian government has dismissed a claim by an Aids expert that the country now has the most HIV-positive people in the world.
It is claimed that Aids is chiefly spread among sex workers
The claim was made by Richard Feachem of the Global Fund to Fight Aids. He says figures showing India having fewer cases than South Africa are wrong.
The United Nations says that South Africa has 5.3 million people infected with the Aids virus.
The Delhi government says there are 5.1 million cases in India.
However, independent experts say the number of people infected in India could be anywhere between 2.5 million and 8.5 million - because of the lack of reliable data here in relation to the HIV pandemic.
India's government-controlled National Aids Control Organisation (Naco) chief SY Qureshi told the BBC that Mr Feachem's claim was "nonsense".
"Our [Aids] surveillance systems are certified by the World Health Organisation, UN agency UNAids and the Indian Council of Medical Research [ICMR].
"We stand by our figure of 5.1 million [infections]," Mr Qureshi said.
Mr Feachem, who is the executive director of Global Fund to Fight Aids, said in Paris on Tuesday that the epidemic in India was spreading rapidly and that nothing was being done to stop it.
Mr Qureshi strongly rejected his comments.
"HIV/Aids is a serious problem [in India]. We are aware of the gravity of the situation and we have programmes to deal with it," he said.
But Indian and international groups working to prevent HIV/Aids have questioned the official figure.
Anjali Gopalan of the Naz Foundation, an non-government organisation working with HIV-infected people, said the statistics did not look reliable.
"We have seen the numbers of the infected grow rapidly. Each and every confirmed case hides at least two more. This means the number of infected could be as high as 15 million," she said.
The Global Fund to Fight Aids has committed more than $3bn to 300 programmes in 127 countries for combating HIV/Aids, TB and malaria.