School sex education classes are not focusing enough on bisexuality, leaving thousands of teenagers exposed to HIV and depression, delegates were told.

Studies from Australia show that youngsters who are unsure of their sexuality, or who are bisexual, feel isolated and disconnected from their peers.

A study from Maria Pallotta-Chiarolli, of Deakin university, Melbourne, found that bisexuality was “invisible” in the school curriculum.

Pupils she interviewed said that most teachers assumed that all children were heterosexual. And even where homosexuality was raised in lessons, there was little if any recognition that some people are attracted to both sexes. “Many young people are left feeling like ‘X-files’ in school: alien, isolated and disconnected,” Dr Pallotta-Chiarolli said.

She found higher rates of anxiety and depression among young people who were identified as bisexuals.

Bisexually-active teenage boys also reported especially high levels of Aids-risk behaviour.