With its high population density and mobile residents, Jakarta is a city at high risk of rapid spread of HIV/AIDS, according to the city's AIDS Prevention Commission.

The organization's head, Rohana Manggala, said that the number of residents known to be living with HIV had reached 42,000. The actual number of people carrying the virus was expected to be much higher, as very few people are tested before developing symptoms of AIDS.

"As we all know, it's the tip of the iceberg, the actual number is much larger. We would like to see the iceberg melt 40 percent to 50 percent as soon as possible," she said on Thursday.

Rohana said there was a large number of people in high-risk categories in Jakarta. "There are more than one million men in Jakarta buying sex, and drug users are easy to find in Jakarta," Rohana said.

She added that there are more than 11,000 intravenous drug users in Jakarta, and more than half of them are estimated to be infected with HIV.