At least 224 children in Roebourne, Karratha and surrounding towns have been identified during a major police inquiry in the Pilbara as alleged victims of sexual abuse, State Government briefing notes have revealed.

Some accused perpetrators are children and attend high schools in the Pilbara region where victims are also students.

Child protection authorities have told school leaders the names of the alleged victims and alleged offenders identified under the long-running inquiry to ensure they could be monitored, according to the documents.

The briefing notes — prepared for Child Protection Minister Simone McGurk last year but only released ahead of a Department of Communities budget hearing tomorrow — provide more details about the highly secretive investigation.

Operation Fledermaus was launched in late 2016 by WA Police to investigate large-scale sex abuse in the Pilbara but senior police and the Government have refused to release many details about what was uncovered.

The secrecy prompted the StateOpposition to warn this year that it was considering asking for a parliamentary inquiry to find out the identities and whereabouts of the alleged offenders.

In July, The West Australian revealed that police had charged 54 men from Roebourne, Karratha and Wickham with more than 360 child sex abuse offences as part of the operation — with more than 180 children and teenagers suspected of being abused.

The briefing notes reveal the number of alleged victims was much higher — and also that the number of alleged abusers in Roebourne was matched by those uncovered in Karratha.

The notes said 224 alleged victims had been identified and other children were being interviewed in Tom Price, Onslow and Port Hedland.

Shadow minister for child protection Nick Goiran said he was troubled by the details in the briefing notes after the Government had told Parliament it was aware of just 42 alleged child victims.

“In October, Sue Ellery, representing Ms McGurk, told me the Department of Communities was aware of all child victims identified under Operation Fledermaus and of where they were living and whether they were going to school, and she said there were 42,” Mr Goiran said.

“Even if you wanted to say there was a difference between a victim who was the subject of charges that have been laid against an offender, from a child protection perspective these are at-risk kids.

“You have a responsibility to be across all 224, not just the ones who end up in court.

“We want to be assured that the minister and her department are across the precise number of victims and that they’re monitoring those victims and their safety.”

Mr Goiran said it was “intolerable” that some accused sex offenders were at high school with alleged victims.

The briefing notes reveal safety meetings have been held at the schools, with a particular focus on education about social media amid concerns online methods were being used to “groom” alleged victims.

It was also disclosed that an accused abuser in Tom Price had his bail revoked after being charged with further offences.

Secrecy still surrounds the identities of those arrested, charged and convicted.