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 from an "old boys' club" parent on Sunday night.