A paedophile caught in a nationwide operation offered to pay a man $500 to experience ''sexual gratification'' with a young boy, according to a police court summary.



The paedophile, Aaron Ellmers, 41, appeared in Hastings District Court this morning and pleaded guilty to a raft of child sex offences that the Crown has described amongst the country's worst.



One of the offences involved Ellmers travelling to Christchurch where a man had offered an 18-month-old boy to him for $500.



The father was arrested and is facing charges related to the incident. He has name suppression.



Ellmers was arrested before he could offend against the toddler.



He pleaded guilty to more than 20 charges making a copy of an objectionable publication and of possessing, unlawful sexual connection with a boy under 12, 11 charges of indecently assaulting a boy under 12, stupefying another person, making an intimate visual recording, making a ''forced labour'' deal using a person under 18 for sex, attempting sexual contact with a boy aged under 2, doing an indecent act to insult and attempting unlawful sexual connection with a boy under 12.



Ellmers was part of an international paedophile ring smashed by police, said Detective Senior Sergeant John Michael, head of the Online Child Exploitation Across New Zealand.



Michael said the operation began in July last year and involved staff across the country and overseas.



Two other men, one in Canterbury and one in Auckland, were also facing criminal charges.



Police also made 35 referrals to police overseas.



Ellmers had served a prison sentence in Australia before being deported to New Zealand.



He lived in Australia between 1999 and 2008. In 2004 he sexually abused an 8-year-old boy, whom he had groomed after befriending his parents.



He served two-and-a-half years in prison and was deported to New Zealand in 2008.



In court this morning Crown lawyer Steve Manning said it was among the worst offending of its kind. He asked for the matter to be moved to the High Court as an application for preventative detention would be made.



Ellmers' lawyer Liz Litt opposed the change of jurisdiction, but Judge Bridget Mackintosh transferred it to the High Court.



An application for name suppression by Litt was declined.



Ellmers will be sentenced in May.



ECPAT Child ALERT national director Alan Bell said the case was a ‘‘wake-up call’’ for New Zealanders, who could no longer pretend such horrific offending only happened overseas.



He said this case was ‘‘one of the worst’’ he had heard of in terms of child pornography production locally, but it was driven by demand.



‘‘This is a very serious case for New Zealand. It should create a strong sense of urgency to strengthen our child protection measures,’’ he said.



Bell said a ‘‘disturbing’’ pattern was emerging of more violent sexual abuses against ever-younger children.



‘‘In this case, the age of the children is particularly disturbing [and] that drugs were used to stupefy. The offender doesn’t recognise the deep and lasting damage they are causing.’’



‘‘It appears this is an organised crime activity. Hopefully there will be other children that can be saved now that ring is starting to be broken.’’



Bell said as a grandfather and father, the idea of accepting money for the abuse of your child was "beyond understanding".



‘‘Some people say poverty is the underlying cause. That’s not something I buy into. They still do have that choice.’’