A Queensland man who allegedly who took on the persona of Justin Bieber to obtain sexually explicit photographs of children has been charged with more than 900 offences.

Gordon Chalmers, 42, was already facing a number of child sex offence charges for possessing child exploitation material, however after detectives combed his computer, he was slapped with another 931 offences that detectives have described as "horrendous".

The man had allegedly been using Facebook and Skype to converse with young children, with some of the offences dating back ten years.

In some conversations, he posed as Canadian pop star Justin Bieber to prey on children’s vulnerabilities.

Many of his alleged victims are Australian children.

A 42-year-old man allegedly posted as Canadian pop star Justin Bieber (left). (AAP)

"The fact that so many children could believe that they were communicating with this particular celebrity highlights the need for a serious rethink about the way that we as a society educate our children about online safety," Detective Inspector Jon Rouse said.

"The breadth of [alleged] offences committed in this instance are frankly horrendous and I want to recognise the efforts and commitment of the investigative team at Taskforce Argos to keeping children safe."

The man was today charged with indecent treatment of children, making child exploitation material, using a carriage service to procure a person under 16, and using a carriage service for child pornography material.

Police are re-emphasising the need for parents to be vigilant with their children's online activity, and will set up a booth at the Out of the Dark Expo on March 11 at Queensland’s State Library to educate parents on keeping children safe online.

Taskforce Argos is a branch of Queensland Police responsible for the investigation of online child exploitation and abuse.