As children have begun returning to the classroom, the Australian Federal Police has issued a grim warning to parents to not post photos of their kids in school uniforms on social media.

AFP Commander for the AFP-led Australian Centre to Counter Child Exploitation (ACCCE) Hilda Sirec said AFP child protection investigators regularly seize images of children in the collections of online child sex offenders.

"We have seen some offenders go to great lengths to gain access to children and in some instances, online grooming has started with information that parents and carers have shared online,'' Commander Sirec said.

"The more information available about a child online, the easier it can be for offenders to build a profile to groom them, or even to groom parents in a bid to access information about their children.

Commander Sirec warns parents to not snap kids in front of homes that show a street number or street name.

"You wouldn't walk up to a stranger and give them a photo album of your children and tell them their names or location.

"We all need to remember that in the digital age, that is the equivalent of posting information and images of children online without the appropriate safeguards."

Commander Sirec says parents can take precautions by locking down their social media accounts so that only approved friends and family can view images of children.

Schools have also been warned about sharing photos of children on school social media pages.

Parents can request their school to not post photos of their children on the school’s social media sites.