HIV/AIDS infections will spread like ‘bushfire’ in parts of India if the country fails to check a spike in the number of intravenous drug users, the United Nations AIDS agency said on Thursday.

India has the world's third highest caseload with 2.5 million infections. It has an estimated 200,000 intravenous drug users, many of whom are in the remote northeast region which borders the opium-producing Golden Triangle of Myanmar, Thailand and Laos.

"If we don't prevent new infections in new emerging populations like injecting drug users, it can go up as bushfires. We may see a major surge in infections," Peter Piot, the Executive Director of UNAIDS, said.

He also raised concerns about the spread of drugs in India. "Drug use is moving a bit everywhere, we can see it in Bihar, UP and in Kashmir, it is kind of moving across the northern part of the country," Peter Piot, head of UNAIDS said.

"I was really shocked to hear what was going on."

Official figures show that more than 10 per cent of intravenous drug users in India are infected with HIV, a higher prevalence than among prostitutes. The country's overall HIV/AIDS prevalence rate is about 0.9 per cent for those aged between 15 and 49.