The number of new cases of HIV and Aids in Singapore fell slightly last year to 454 - 15 fewer than in 2012.
However, Action for Aids (AfA) said there had been a "worrying" rise in infections among homosexual men.
The Ministry of Health revealed the figures yesterday, which also showed that the number of homosexual and bisexual cases had risen from 166 in 2009 to 247 last year. In contrast, the number of heterosexual men infected fell from 241 to 157 in the same period.
Around a decade ago, men who contracted HIV through gay sex accounted for less than 30 per cent of male infections, but they now make up more than 60 per cent.
A spokesman for AfA said the rise in homosexual HIV transmission could be because people are not as fearful of contracting the infection as previously, due to the availability of effective anti-retroviral medication.
However, he said that there was a degree of "condom fatigue" in Singapore.
While surveys showed that the rate of condom use had remained steady at about 50-60 per cent, he said this was "unsatisfactory".
The group added that social media had made it easier for people to hook up for casual sex.
Since 1985, 6,454 people here have been infected, including 155 diagnosed this year. More than a quarter have died.
Amy Khor, Senior Minister of State for Health, said that there must be no let-up in education and outreach efforts, adding: "The best way to prevent HIV infection is to remain faithful to one's spouse or partner, avoid casual sex or sex with sex workers and use condoms."
She also urged people in at-risk groups to get screened, to allow for early diagnosis.
This article by The Straits Times was published in MyPaper, a free, bilingual newspaper published by Singapore Press Holdings. Get a copy of The Straits Times or go to straitstimes.com for more stories.