Four Canberra youths — including two teenage brothers — who were accused of running a blackmail scam targeting gay men on dating apps are denied bail.

The alleged scam came to light last month when the AIDS council raised concerns about people targeted by the group.

The youths allegedly lured men using dating apps, before demanding money amid threats of exposing them.

The amounts demanded ranged from $150 to $1,000.

A 15-year-old, two 16-year-olds and an 18-year-old appeared in the ACT Magistrates Court today, where each was denied bail.

Police told the court one of the alleged victims in New South Wales had taken his own life.

The court heard other victims had been identified by material found on social media and other accounts belonging to the group, as well as stolen mobile phones.

But police told the court most were reluctant to complain, because of embarrassment.

The court heard one of the boys told police the people they were targeting were paedophiles.

Police argued against bail, citing concerns there could be a risk of interference with evidence or witnesses.

Magistrate Margaret Hunter agreed, rejecting arguments from the lawyer for the 18-year-old that he was only charged over one of the incidents and had nothing to do with the alleged victim who had died.

"This appears to be a gang scamming this unfortunate individual," Magistrate Hunter said.

"The modus operandi is significantly similar. It's highly unlikely it's a coincidence."

The four will be back in court next week.