A group of underage teenagers are accused of extorting older men they met through the gay dating app Grindr.

Police have launched an investigation into an alleged blackmail scam, by which the teens threatened to “out” their targets as pedophiles if they didn’t hand over cash and mobile phones, according to The Canberra Times, an Australian newspaper.

The police took action after the AIDS Action Council in Canberra began receiving reports of extortion.

Last week, four teenagers between the ages of 15 and 18 were charged with offenses linked to the alleged syndicate. Three of the boys are underage. They cannot be named for legal reasons.

Police seized digital evidence from the boys’ mobile phones.

According to The Canberra Times, the boys would create whole documents on their victims, including photos, screenshots of conversations and possible crimes they had committed, a court heard.

They would then demand $750 and mobile phones, threatening to report the men to the police if they didn’t comply.

Prosecutors said the offenders contacted the men through Grindr or Facebook and, upon meeting face-to-face, told them they’d been communicating with minors.

One boy allegedly told one of the victims: “We’re the pedo hunters.”

It’s possible there were up to 10 offenders, and up to 15 men were preyed upon.

Last month, the AIDS Action Council warned of perpetrators using a similar scam on Grindr by threatening to “out” closeted men who used the app.

“We’ve put out this warning to alert people that there has been a couple of incidences,” director Philippa Moss told the ABC.

“When (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.”

It’s understood the perpetrators would earn the users’ trust online and then threaten to expose them in person if they didn’t pay up.