A cyber-security expert in Australia has warned parents of the risk of sharing children's photos online. Nearly half of the content found on some paedophilia websites was found to be sourced from social media sites, like Facebook and family blogs.

Australia's Children eSafety Commissioner, Alastair MacGibbon, said while the photos might appear innocent; comments exchanged under the images sexualized them. Amongst the images retrieved by investigators, most of them were found to contain children doing everyday activites, swimming and sports.

"Many users clearly identify that they have obtained the content through trawling social media accounts. The images are almost always accompanied by highly explicit and very disturbing user comments. Often, users exchange email addresses with invitations to connect outside the site to trade content," said MacGibbon, reported The Sydney Morning Herald.

MacGibbon warned parents on taking caution and said better efforts need to be made since there are several cases of parents taking "no security against these obsessive efforts to obtain content." Once an image is shared, it can be easily downloaded by friends and strangers, warned MacGibbon.

The images were found to be sorted into categories by social media sites that they had been downloaded from, said Toby Dagg, senior investigator at the eSafety Commissioner. Some folders, included 'Kik girls', 'my daughter's Instagram friends', and other labels, like 'kids at beach' and 'nice boys play in river'.

"When you post anything online, does not matter where it is, you have lost control of it," said Cyber-safety expert Susan McLean. "Many parents do not lock their accounts down in the same way kids do. 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."