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New Zealand authorities have claimed credit for sparking an international child porn investigation that led to arrests worldwide.
The Department of Internal Affairs (DIA) said it triggered the investigation that ultimately led to more than 100 arrests.
At least 40 exploited children were rescued because of the police sting, which uncovered about 400,000 images of abuse from the group which operated in Australia, the United States, England, Canada and Germany.
No New Zealanders were thought to have been arrested.
The DIA has inspectors who enforce censorship and promote internet safety.
"We have a censorship compliance unit. They spend their time tracking offenders on the internet who are trading in these sort of child sex abuse images and downloading them," said the DIA's Trevor Henry.
He said the sheer volume of encrypted material being traded by people was what first sparked inspectors' interest.
"They (inspectors) know what to look out for. They have powers under our laws to be able to locate who is doing it through the ISPs (Internet Service Providers) and so on," Mr Henry said.
"In the course of this work they came across this group. One of the kingpins was an Australian."
Mr Henry said there were many gigabytes of information, mainly video and photos of violent sex abuse, being traded by the group using innocuous subject names such as "gardening" or "cars".
It is understood children as young as two were sexually abused to fulfil orders from an online network.
When it was learned some of the information was passing through an Australian ISP, the encrypted material was given to Queensland police, Henry said.
From there, Queensland officers took charge of the investigation, tracking the material to Europe, where it led to various arrests.
Among those taken into custody were an Italian filmmaker and website creator, and a Belgian father whose two girls were abused.
The police sting ultimately became controlled by the Federal Bureau of Investigation (FBI) and was based in the US, where most offenders were located.
"I think we picked it up in August 2005 and continued to work on the stuff, then passed it onto the Queensland team in January 2006," Henry said.
"Basically we sparked the thing off, then Queensland took over and it involved Australia, the UK, Canada, Europe. It was a big ring," he said.
- AAP
