Investigators looking into complaints of online child abuse material had discovered tens of millions of photos of children sourced from popular social media sites.
Most of the pictures were originally posted by the parents,
who are unaware of how easily they can be downloaded and stored by strangers, Children's eSafety Commissioner Alastair MacGibbon said.
Senior investigator at the eSafety Commissioner, Toby Dagg said that on one site with at least 45 million images "about half the material appeared to be sourced directly from social media" and clearly labelled in folders as images from Facebook, or other social sites like Kik, with one folder called "Kik girls".
All the pictures on these image-sharing paedophile sites were not explicitly sexual but even the pictures of innocent children doing everyday activities like swimming or sports were accompanied by sexual comments.
"It does not matter how innocent the photo is, if your child has got what a predator is looking for, they will take that photo," Cyber-safety expert Susan McLean said and advised parents to set up limited locked groups on Facebook before sharing images.