Men using gay hook-up apps and forums are being blackmailed by a group of three or four people in Canberra, the AIDS Action Council warns.

The ABC understands the perpetrators earn users' trust online but when they meet in person they threaten to expose them if they did not pay them money.

Online safety tips: Double check they are who they say they are.

Double check they are who they say they are. Meet in a public place the first time.

Meet in a public place the first time. Always tell someone where you're going.

Always tell someone where you're going. Listen to your gut - if you feel unsafe leave. Source: AIDS Action Council

The AIDS Action Council received two separate reports from victims this week but fear there may be more who are too embarrassed to come forward.

"We've put out this warning to alert people that there has been a couple of incidences," director Philippa Moss said.

"When they [the victims] have turned up they've been blackmailed and ended up in unsafe situations.

"[They said] they're going to exploit them, if they don't give them money they're going to tell their friends and family what they're doing."

Ms Moss said the targets could be vulnerable.

"People don't necessarily admit that this is what they're doing. There is stigma and discrimination attached to using these apps for hook ups," she said.

"What these people are doing in terms of blackmail and extortion — that is a crime and needs to be reported so these people can be caught and stopped."

Council to run online safety forum

As well as reporting the scam to police confidentially, Ms Moss said victims could contact the council for support.

"Come and have a chat, we've got lots of councillors here who can guide them in the right direction," she said.

The council is also planning to run a forum about online safety over the next few weeks.

"I think people get a bit blase about online safety," she said.

"There's so many apps out there that you can use and it's a great way to meet people but please be safe."

The ABC has contacted ACT Policing for comment.