Lexy Zhang laughs nervously as he talks about his first experiences picking up men for sex in a country where condoms are widely available for family planning but not always promoted to prevent AIDS.

“I was just having unsafe sex all the time,” said the 26-year-old, sitting in a fashionable Beijing bar frequented by gay men.

“Lots of gay Chinese think it’s great that you don’t have to worry about pregnancy but have no idea about sexually transmitted diseases,” said Zhang, adding he now would never consider having unsafe sex.

“There are just not enough organizations paying attention to this community. The government thinks it doesn’t exist.”

How to prevent the spread of AIDS in places like China will be a major focus of researchers and policymakers at the 16th International AIDS Conference, which opens on Sunday in Toronto.

In China, homosexuality, while no longer officially considered a mental disorder, is still an off limits subject for many. That taboo often extends to discussions about AIDS and condom use for men who have sex with men.

Condoms are widely available thanks to China’s long-standing one-child policy, but conservative attitudes and an unwillingness to talk about sex mean the connection with AIDS prevention is not always made.

“Sex is taboo, and condoms have mainly been used as part of family planning rather than for safe sex,” said Lee Folland, a graduate student doing research at Cambridge University on the social marketing of condoms in China.

In a Beijing survey, only 15 percent of 482 men who had sex with men understood that they were at risk of contracting HIV, according to a 2005 report by the United Nations’ UNAIDS. Some 49 percent reported having had unprotected anal intercourse with men in the prior six months.

A survey in late 2004 by the Chinese Center for Disease Control and Prevention in the northeastern city of Harbin found that almost 20 percent of men who had sex with other men also slept with women. More than 10 percent were married.

“There is strong social pressure to get married - or what would the neighbors say? It’s not only about how your parents would react, but how others will react to your parents,” Folland said, referring to fear of social ostracism for parents whose sons were thought to be gay.

Condoms and safe sex information are often not available in Chinese gay bars or saunas. Although they are starting to appear thanks to volunteer groups and outreach programs and a government belatedly waking up to the problem.

But even that information can sometimes be too tame to include pictures of how a condom is used.