STV News say photographs have been taken from school social media pages and posted on a site described as “meeting place for paedophiles”.
The broadcaster says the pictures of the children are innocent but have been placed alongside extreme images of babies, children and teenagers.
Joanna Murphy, chair of the National Parent Forum of Scotland, told STV: “It makes you feel sick to your stomach that somebody is looking at your children’s photos, for example of them winning a prize at school.
“We need to all be much more mindful about what we’re doing, what we’re sharing and how we’re sharing it.
“It’s not the fault of local authorities or schools or young people but we need to make sure it’s not happening as widely. I think there is a part to play for government to look into this.”
The broadcaster said affected schools included Glasgow Gaelic School, the city’s St Mungo’s Academy, Our Lady’s RC Primary in Perth, Stirling High School and nearby primaries St Ninian’s and Gargunnock.
Another school targeted was Dallas Primary in Forres, Moray.
Digital forensic consultant Vassilis Manoussos, manager of Napier University’s cyber academy, said: “A lot of these comments are vile and inappropriate and unfortunately there’s a lot of people like that out there.
“It is disturbing that there is one place where so many pictures of children are collected and people are actually urging other users to add to this collection.”
The Scottish Government told STV: “Internet services and their regulation is a reserved matter and the Scottish Government is fully engaged in the UK Government’s current consultation on proposals to establish in law, a duty of care for service providers to their users as well as creating an independent regulator that will hold tech companies and providers of online services to account for tackling online harms.”
Chief Superintendent John McKenzie, of Police Scotland, said: “Whenever we receive information to suggest that a child or young person is at risk of abuse we will pursue and target those individuals involved, collaborating with a range of partners across the UK and around the world to bring these criminals to justice.
“The internet is no hiding place for abusers.”
A Glasgow City Council said: “Unfortunately there’s nothing that we can do to completely eradicate this risk - but schools can help by pixilating names on certificates that could lead to identification and parents have a role to play to make sure their children are following internet safety guidelines.”
Moray Council’s acting education and social care director Graham Jarvis said “It’s common practice for schools and parents to share pictures of their children to celebrate successes and activities, and it would be a great shame if the actions of a few depraved individuals prevented this.”
A Perth & Kinross Council spokeswoman said: “Unfortunately, as this situation exemplifies, there may always be individuals who wish to make entirely inappropriate use of images of children and young people.”
Wellington headmaster Simon Johnson: “Like all independent schools, we have policies in place regarding the use of images and these are reviewed regularly.
“Indeed, the recent introduction of GDPR legislation prompted significant changes in exactly this area. The story that you are telling, of course, will help us to refine our thinking in the future.”