SINGAPORE - A mobile white van offering anonymous testing for HIV (Human immunodeficiency virus) and syphilis in Singapore has drawn more to take the test since December last year, local daily Straits Times reported on Wednesday.

About 500 people have taken the test over the past six months as the van went from car park to car park to provide the testing services, said advocacy group Action for Aids, which operates the van.

One person tested positive for HIV and another for syphilis, the group said.

About two-thirds of those who took the test are aged between 20 and 39, a demographic that overlaps with the 29-and-below age group whose HIV infection rate has risen sharply in the last seven years.

It is encouraging that the number of people being tested in areas such as the red-light district Geylang, is growing.

"These days, there are even short lines of people waiting to get tested in Geylang," a spokesperson for the group said.

The growing popularity of the mobile testing service seems to stem from the "anonymity, convenience, and how quick and easy the testing process is," according to feedback received, the spokesperson said.

The test costs 30 Singapore dollars ($24) and takes about 30 minutes.

Roy Chan, founder and president of the group, wants to spread the service to more locations "to reach out to persons who are at risk of HIV infection but who, for whatever reasons, are afraid to go for testing at clinics."

HIV testing is offered at public hospitals. However, a recent study by local hospital Tan Tock Seng Hospital found that eight in 10 patients refuse to be tested.

Anyone who tests positive for HIV using the mobile service is urged to go for a more comprehensive blood test at its Anonymous Test Site, located in a clinic run by the Department of Sexually Transmitted Infections Control.

The Anonymous Test Site, which does HIV testing three times a week, saw an average of 560 people each month in the last six months.

In the last seven years, the number of young people in Singapore diagnosed with HIV has doubled, the Straits Times said, citing Health Ministry statistics.

Almost 100 people aged 29 and younger tested positive last year, compared with about 50 in 2005. Altogether, 461 people tested positive last year, 20 more than in 2010.