The AIDS Action Council says gay men using hook-up apps in Canberra are being targeted by extortionists who threaten to reveal them to family and friends if they don't hand over money.
The organisation has contacted ACT Policing after two men reported the scam. Each man was arranging to meet with someone from Grindr when they were blackmailed and threatened.
"They've been supposedly blackmailed in terms of 'I will make it known who you are' and that sort of thing around using the hook-up apps, extorting them for money, and there has been some indication of potentially meeting them and then beating them," AIDS Action Council director Philippa Moss said.
"We've reported it to the police of course and we offer counselling services at the AIDS Action Council so there's lots of support in the community if people do feel that they need to talk about these things or it's alarming for them."
Ms Moss likened the incidents to attacks on sex workers in Canberra last year. She said anecdotal evidence indicated a group of three or four men were behind the accounts.
"Maybe it's about stigma and discrimination," she said.
"In that sense obviously those men had a problem with sex workers. Maybe - maybe - this group of men have a problem with gay men or people who are HIV positive, so it's about breaking those stigma myths."
Ms Moss emphasised people meeting someone from online should always let others know where they were going.
"There's a whole lot of things people can do to keep themselves safe in terms of making sure that they're telling someone where they're going, meeting in a public place, if you've got any sort of niggling feeling this is not safe, don't turn up, don't go, follow your gut instinct on what might not be safe," she said.
ANU College of Business and Economics Associate Professor (Information Systems) Sigi Goode also shared some tips on spotting fake accounts online.
Recently made accounts, brief interactions and commonly found account names could be indicative of a fake account, he said.
"The obvious one is a reverse image search leads to multiple duplicates online. If they use a photograph they may have ripped it from Facebook or Pinterest or whatever," he said.
"[There might be] inconsistent or sparse information associated with the account, so they might say they lived in one state but their primary school is another state or something like that.
"A web of trust approach can work, so tracing back to look at friends so they look like they're viable, and behaviourally, fake accounts often ask for money very early on."
An ACT Policing spokesman urged people to contact police if they fell victim to the scam.
"ACT Policing encourages everyone to think of their personal safety when meeting people and would encourage if anyone has been a victim of physical violence, blackmail or extortion they come forward and speak with police," he said.
Ms Moss also encouraged people to anonymously report such crimes via Crime Stoppers.