Ian Roberts, the first elite rugby league player to come out as gay, said Australian sport had not done enough to stop homophobia, as studies on Wednesday highlighted the level of discrimination faced by young lesbian, gay and bisexual athletes.

Two Monash University studies found most lesbian, gay and bisexual (LGB) athletes were unwilling to reveal their sexuality to team mates while more than half of male LGB athletes had been the target of homophobic behaviour.

Australian rugby league international Roberts, who came out in 1995, said the findings showed the country’s top sports federations had made “empty promises” when they signed a formal commitment to eliminate homophobia in 2014. “It has been a quarter-century, I hate to think about that, but truly it has been a quarter-century since I came out,” the 55-year-old said on Wednesday.

One of the Monash studies found 82% of male and 77% of female LGB athletes tried to hide their sexuality from at least some of their team mates in survey responses from more than 1,000 LGB youths in the United States, Canada, Britain, Australia, New Zealand and Ireland.

Just 20% had come out to everyone on their team.

The study showed 52% of males and 36% of females reported being the target of homophobic behaviour in team settings.

Those who came out to any of their team mates were “significantly more likely to report being the target of homophobic behaviours”, the study said.