"Detectives had been investigating a man who allegedly posed as Justin online in order to solicit explicit images from young children," Queensland state police said in a statement.
"As part of the investigation, a 42-year-old man had earlier been charged with a number of child sex offences including possessing child exploitation material and using a carriage service to groom persons under 16.
"After a thorough examination of the man's computer, he has been further charged with another 931 child sex offences."
The charges include rape, indecent treatment of children, making child exploitation material, using a carriage service to procure person under 16, and using a carriage service for child pornography material.
Detective Inspector Jon Rouse described the breadth of offences as "horrendous" and urged fans to be extra vigilant when using the internet.
"This investigation demonstrates both the vulnerability of children that are utilising social media and communication applications and the global reach and skill that child sex offenders have to groom and seduce victims," he said.
"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."
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