Online predators are increasingly resorting to "sextortion" - blackmailing child victims into providing explicit images.
Internet safety watchdogs say they are seeing new trends in the methods used to extort kids as young as 8 into sending pictures of themselves to perverts, who often masquerade as youngsters online.
Netsafe executive director Martin Cocker said children could end up in a tangle "difficult to unravel" and too scared to tell those who could help them.
"We see a pattern where a young person provides some pictures and the adult asks for something more risque - and more, and more until they say, ‘no'. And then they say, ‘I'll send those pictures out to your friends and people you don't know if I don't get what I want."'
Detective Senior Sergeant John Michael, who leads the Online Child Exploitation Across New Zealand (Oceanz) unit, said police were now dealing with similar cases every few weeks - with most offenders based overseas.
Few ever made contact in person, but they still had the potential to hurt and humiliate online, he said.
Educational psychologist Fiona Ayers said children who had difficulty socialising would be more receptive to a stranger's advances and more likely agree to supply risque photos.
"Abusers are able to persuade kids to do these things because they think it's part of a friendship when, really, it's grooming."
Mr Michael said while kids technically had to be 13-years-old to have a Facebook profile, many younger children were on the site. Police had dealt with victims as young as 8, he said.
Offenders could create fake social media profiles to befriend youngsters and, once they had gained their trust, would request mildly sexual images.
Those images would then be used for "sextortion", with the predator threatening to leak them unless more explicit material was provided.
The victims' families often had no idea about the extortion until police showed up on their doorstep, he said.
Oceanz was investigating a New Zealander thought to be involved in online exploitation of children abroad, he said.
Last year, Wellington man Graham MacDonald Young, 60, was jailed for making and possessing objectionable material. He created a fake online persona using photographs of former Shortland Street actor Adam Rickitt to persuade a 13-year-old girl in New York to send pictures of herself.
Detective Senior Sergeant Neil Holden, of Wellington district child protection, said parents had to understand how new communication technology worked. "Parents like to know where their children are. It's also important they know where they are online."
Mr Michael said teaching children to be cynical about their internet "friendships" could help them be more wary online.
SIGNS A CHILD MAY BE IN TROUBLE ONLINE
The proliferation of devices such as smartphones and tablets that can go online wirelessly means it is harder to monitor what kids are up to online.
But Fiona Ayers, of Psychology for Children, says there are warning signs: They go on the computer at the same time every day.
They are secretive when they use the computer or leave the room with internet capable devices.
They are very happy when getting off the computer.
They are depressed, down or withdrawn.
Their behaviour changes.
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