Innocent photos of children - originally posted on social media sites - account for up to half the material found on some paedophile image-sharing sites.

It's a finding of the Australian Children's eSafety Commissioner, who has warned people about sharing photos of their children on Facebook, Instagram and other social media sites.

Alastair MacGibbon says a lot of the material found on certain pedophile sites had been sourced or stolen from parents innocently posting images of their families on line.

Chief Executive Officer with the ISPCC Grania Long says it's important that parents think before they post: