A convicted child rapist was reportedly paid nearly $13,000 by British police to spy on a network of nearly 20 people drugging and abusing young women and girls.

Newcastle prosecutors said the Northumbria police paid the man – referred as "XY" and only identified as a British Asian man – more than $12,500 over 21 months to find out the times and whereabouts of parties where girls were being given drugs and alcohol before they were abused.

The news comes after the 17 men were convicted of rape, sexual assault and drug offenses during a series of trials at Newcastle Crown Court.

One woman, identified as Carolann Gallon, 23, was convicted on three counts of trafficking for sexual exploitation.

The victims ranged in age from 15 to their early 20s. Reporting restrictions prevented details of the case from emerging until now.

The police’s actions to pay the convicted rapist for information and “plant him in the midst of vulnerable young girls” raised serious questions about the how the police handle child sexual exploitation operations, according to the UK’s National Society for the Prevention of Cruelty to Children.

“You just couldn’t make it up,” Jon Brown, head of development at NSPCC, told the Guardian. “It beggars belief that it would ever have been considered, let alone approved, and serious questions must be asked about the force’s approach to child sexual exploitation operations.”

He added that while the force had good intentions, the misguided actions ran “entirely counter to all current child protection procedures and what we know about sex offenders.

“What we mustn’t forget in all this is the victims who were preyed on by a serious of despicable men for their own sexual gratification,” Brown added.

Lawyers acting on behalf of the defendants attempted to get the cases thrown out because of XY’s involvement, arguing that he was unsuitable to be an informant, the Guardian reported.

Robin Patton, representing one of the defendants, said XY was convicted in 2002 of raping a child after he drugged her and invited someone else to rape her as well.

After he was recruited by police, XY was arrested in 2015 on suspicion of a sexual offence against an underage girl who claimed a man approached her and made an indecent proposition. The case was later dropped, the Guardian reported.

During the hearing, XY – speaking behind a screen – said he felt he was “doing good” when he worked for police.

He said he was recruited to act as a taxi driver for some of the defendants.

“I would get to know where they pick up their drugs, where the parties were,” he reportedly said during the hearing. “I was chilling with the boys. I had to make it look like I was their friend.”

According to the Guardian, XY also made a series of allegations against the police, but judge Penny Moreland, dismissed them as “inherently unreliable,” “lacking in credibility” and “clearly dishonest.”

Moreland also dismissed calls to get the case thrown out, saying that there was not evidence that “any of the proper procedures for the handling of informants were breached, or of any improper conduct.”

She also said there was no evidence that XY was guilty of any sexual misconduct toward the complainants.

Northumbria police’s chief constable, Steve Ashman, defended his force’s decision to engage with XY despite understanding it “may appear repugnant.”

“However he proved he was in a position whereby he could, and did, alert police of situations which allowed them to prevent offending and provide safeguarding measures towards potential victims,” he said, according to the Guardian.

The Associated Press contributed to this report.