Police are investigating an Instagram account which was set up by students at an exclusive private boys' school to share photos of young girls without their knowledge.
The offensive account was created by two Year 11 boys at Brighton Grammar School and encouraged viewers to vote on the "slut of the year".
Brighton Grammar suspended the students on Monday and will make a decision on their future at the school following an investigation.
A Melbourne mother who spoke out in disgust on her Facebook page after discovering that photos of her young daughter were uploaded onto the social media page, told Fairfax Media that she received a threatening phone call from an "old boys' club" parent on Sunday night.
The caller, who phoned on a blocked number, said the Instagram account "was just a group of young boys having fun".
"It was an attempt to intimidate me, but it won't happen," the mother said. "I'm determined to make sure that everyone within our community thinks twice, and has a heightened sense of the dangers of social media."
The mother reported the vile account to police on Saturday after discovering girls as young as 11 or 12 on the account in various stages of dress.
A police spokesman confirmed they had received a report about "inappropriate content on an Instagram account originating in the bayside area".
"The matter is being investigated by local detectives and as the investigation is ongoing, it would be inappropriate to comment further at this time," the spokeswoman said.
One photo apparently showed a schoolgirl wearing bikini bottoms and a white singlet top and included a caption describing sex acts she would perform, the mother said. Another photo featured a group of grade six girls in their school uniforms as they walked to meet their parents after school.
"I am writing this as a mother of a girl that has not only been sexualised but violated within our small community," the concerned mother wrote on a public Facebook post, which was shared hundreds of times before she made the post private on Sunday night.
"I will not rest until the consequence for the crime meets the severity of the crime itself - for my daughter and all other young unsuspecting girls."
The mother said she did not blame the school - but blamed the boys' parents. "The school has done everything in their power. Education begins at home."
The account – which was titled ys_academy_puspus – was set up by the students after school on Friday and deleted over the weekend after Brighton Grammar became aware of its existence. It is understood that YS stands for "young sluts".
Headmaster Ross Featherston has spoken to the boys involved, their parents, and the parents of at least two girls whose photos were shared online.
He addressed the senior school boys on Monday morning and said staff were taking the matter very seriously.
"The Instagram post is disgraceful and does not reflect the values of BGS," Mr Featherston said in a statement released on Monday morning. "Disrespectful behaviour on any social media site is simply unacceptable and will not be tolerated."
He said Brighton Grammar regretted the distress that the incident had caused the girls and their families.
He said the behaviour of the two students did not reflect the values of Brighton Grammar, and respectful relationships were a "critical part" of the school's culture.
The school is still determining what sort of punishment the students will receive, and is in discussion with the boys' families.
Fairfax Media has not named the mother in order to not identify her daughter.
PS Tweet from Jane Caro tonight (21/07/16)
@JaneCaro Brighton Grammar students 'leave the school' after scandal. Public schools must welcome such students regardless of disruption.