Facebook has removed a group from its platform which was sharing images of Northern Ireland schoolgirls.
The group, called "The Best School Girls" said it was to be used for "sharing photos of pretty girls".
The PSNI said three reports had been made about the group to it but officers had not found criminal behaviour.
The page, however, remains under investigation and police appealed for anyone with information to contact investigators.
Police also warned people of the dangers of sharing information online and offered advice.
"We understand the distress young people and their parents/guardians must feel when they see images taken from their own accounts and circulated on pages like this," police said in a statement.
"We do not underestimate how difficult it must be and the urgency in which you would want those images removed."
Girls from across the world were included on the group, including some from Northern Ireland.
The images were taken from social media profiles and then shared on the group.
A PSNI spokeswoman said policing social media was "complex".
She said: "[We have] received three reports to date in relation to a Facebook page that has been set up called ‘The Best School Girls’ which shows images of girls from all over the world in their school uniform, taken from their own public social media accounts.
"The reports made to the police to date have been investigated and the images were found to have been posted by the page in question and taken from accounts already in the public domain."
She added: "Policing social media is complex and there are definitions of what constitutes a criminal offence in these online spaces.
"Offences online may include, pictures that show nudity of children or indecent images of children, threats to kill, threats to cause damage, criminal conduct amounting to harassment and comments that incite racial hatred, violence or rioting.
"As the photos investigated by the Police to date were already open to the public and showed no nudity, no criminal offence was found. "However, the nature of this page is still under investigation and will remain open. Police will continue to investigate and encourage anyone who is aware of images or commentary on this page that would constitute a criminal offence to come forward and report."
A spokeswoman for Meta - Facebook's parent company - said: "We remove Facebook profiles, pages, and groups that are dedicated to sharing otherwise innocent images of children with captions, hashtags or comments that contain inappropriate signs of affection or commentary.
"We have removed this Facebook Group for violating our policies."
Police said they are working in partnership with the Education Authority and schools to "educate young people and their parents about the potential dangers online and how to navigate these social media platforms safely".
The PSNI spokeswoman continued: "All social media platforms have a duty of care to their users and we ask that those who use social media sites take steps to protect themselves and the copyright of their images."
Police offered advice to social media users:
1. Always think carefully about any information you choose to share online as it leaves a digital footprint. 2. Take time to set your privacy settings and check them regularly to stop people you don’t know accessing the information you choose to share on your own platforms. 3. Be aware who you are adding or interacting with online. 4. Choose a strong password and secure your accounts. 5. Report to the social media platform any content you find inappropriate so action can be taken to remove this from the site.