Police officers have been called into primary schools where boys as young as 8 had taken secret photos of girls getting undressed and posted the pictures online.
A growing number of primary school children are seeking help for unwanted cyberbullying attacks - and those harassing them are likely to be the same age.
Psychologists, internet safety experts, educators and police have voiced alarm at the number of youngsters involved in online bullying and sexual exploitation.
West Auckland school community officer Senior Constable Paul Stanko said he had been called in to several primary schools after 8-year-old boys had cyberbullied their peers.
"There's been cases where inappropriate photographs from school camps, boys trying to get pictures of girls undressing and that sort of thing, have been posted online and saying silly things where they've not realised what they are actually saying."
Mr Stanko said in these cases the emphasis was placed on educating the youngsters to behave differently.
"I speak to the whole school - the children aren't often singled out, but the classrooms are together - and if necessary I'll speak to the parents as well and give advice."
Crisis help agency Kidsline said children as young as 7 were now phoning for help with cyberbullying.
Chief executive Jo Denvir said it was a national shame and that there is a lack of boundaries in homes for young cyber citizens and adults are providing a poor example of how to behave online.
YouthLine psychologist Bridget McNamara said more girls than ever aged between 11 and 14 were seeking help over sexual exploitation.
NetSafe's Martin Cocker said a number of advisory groups in the schooling sector were reporting a growing number of cyber harassment and bullying incidents involving children from intermediate and primary schools. Many children were copying older siblings and celebrities and sending naked selfies on social media.
"The sharing of those is really quite common among youth, and younger children see that behaviour from their older siblings or from other media figures," Mr Cocker said.
"Once those images are created then shared with another audience you've got everything required for harm to be done to that child."
He said young children were also drawn into difficult online relationships with exploitative older people.
Online Advisory Safety Group spokesperson Patrick Walsh said the prevalence of pornography had had a hugely adverse influence.
"Students as young as 12 are exposed to explicit pornography and some of that's quite violent, so they grow up at those critical ages when they're forming relationships thinking the sort of behaviour they see on the web is actually normal."
This is echoed by New Zealand Intermediate and Middle School president Doug McLean: "It's getting younger and I think the worrying thing is some of the stuff that kids are looking at is desensitising them."