Eighteen people have been found guilty of grooming young girls in Newcastle, plying them with drugs and alcohol before abusing them at "sex parties".
Carolann Gallon, 22: Convicted of three counts of trafficking for sexual exploitation.
After he was recruited, XY was arrested in September 2015 on suspicion of inciting sexual activity with a child after a teenage girl claimed a man approached her and made an indecent proposition.
Police said last night that paying the offender for information allowed them to put "dangerous men behind bars".
Jon Brown, lead expert on tackling child sexual abuse at the NSPCC, said: "We are appalled to learn that police paid a child rapist and planted him in the midst of vulnerable young girls". "What we mustn't forget in all this is the victims who were preyed on by a series of despicable men for their own sexual gratification".
Poll: were police morally right to pay a paedophile to inform?XY said his handler was only interested in gathering evidence on Asian males.
Judge Penny Morland dismissed the application to throw out the case, but described XY's evidence as "inherently unreliable" and "clearly dishonest". "There is no evidence that any of the proper procedures for the handling of informants were breached, or of any improper conduct".
The force's police and crime commissioner Vera Baird said it was a hard decision to use XY.
'It's an Asian, Muslim operation.
The informant, who is on the Sex Offenders' Register, was later told he would face no action after he took part in an identity parade.
'The police were happy for him to be going to parties, taking drugs, being out of control because of the high value of the information.
Helen Beckett, an expert on child sexual exploitation from the University of Bedfordshire, said focusing on one ethnic group risked missing other patterns of abuse. The court heard that XY was also subject to a suspended sentence at the time that he was paid by police.
Some experts say the focus on South Asian perpetrators masks how widespread child sexual abuse is, and overlooks the fact that victims are often ignored by authorities due to their youth and troubled backgrounds.
"You turn over a stone and you will find this kind of behavior pretty much everywhere in this country", he said. Two officers and myself.
He said: 'I was a one-off.
The informant told The Sun he was "good" at what he did and ended up helping the police.
United Kingdom police paid a convicted child rapist nearly £10,000 ($13,000) to spy on people - including suspected underage girls - at sex parties, it can now be reported.
'There were certain individuals they were very interested in, which I was close to'.
The people that XY informed on. He also claimed that he was instructed to plant drugs in the home of one of the defendants. XY said: 'I was chilling with the boys.
'No matter what I do, it will affect my family'.
"I feel so passionately about this that I would like to apologise to any rape victims who feel they have been let down by this".
The court heard how XY had complained to the National Crime Agency about the police and his allegations have been referred to the IPCC.
However, officers did not deny the possibility that he was in rooms with girls during his deployment.
He added: 'The handlers have been nothing but supporting. "I had to make it look like I was their friend".
Northumbria Police Chief Constable Steve Ashman said in a statement: 'We know concerns have been raised about our use of a police Informant known as XY.
"In the case of XY it is clear that his relationships with others have allowed the police to prevent and detect some of the most serious crimes occurring in our communities, this would not have been possible through conventional methods".