Gold Coast school students have been caught up in an online sex extortion scam, where predators are blackmailing them for cash.

The criminals are threatening to upload naked photographs of the young victims, unless they hand over money.

At least two students at Helensvale State High School posed naked for a stranger online.

The sexual encounter then turned into sexual exploitation.

"It's appalling. Unbelievable… It's pretty scary when they're on there. It's hard to monitor them too,” a parent told 7 News.

"I think kids hide their phones from their parents and get away with a lots of things.”

The school has since warned parents saying young people were lured to connect on Skype by an attractive teen and encouraged to remove their clothing.

The predator records video and pictures.

Then the teen's Facebook account is hacked and an amount of money is requested to avoid these images being shared with their friends.

Police say the scams are becoming more common and elaborate.

“It gets to the point where it goes from a conversation to demands,” Detective Inspector Mark White said.

They're worried many teens are too embarrassed to come forward, choosing instead to suffer in silence.

"There are victims out there that don't report it because they're fearful of what might happen,” he said.

Principal Mark Blackshaw said he encouraged students to own up and seek the support because it's not going to go away.

"Stuff remains there. It can haunt people for the rest of their careers."

Staff members say they're being proactive by making the school community aware of the threat, but ultimately it's up to parents to monitor who their children talk to online.