The Ministry of Social Development is being accused of a mass breach of privacy after it sent details to police about children abused in state care, despite some victims saying they didn't want a criminal prosecution.
Three complainants who say they were abused while in state care are about to lodge a complaint with the Privacy Commissioner.
The complainants' lawyer, Amanda Hill of Wellington firm Cooper Legal, said it was likely hundreds of other cases had also been passed on to police.
"We're saying that it's wrong that a government department can initiate a mass disclosure of sensitive information to the police without consent of the plaintiffs - that's a breach of privacy."
The ministry signed a protocol with police in May 2016 about sharing information. The ministry says it is obliged to share the allegations with the police as part of the protocol, aimed at protecting people from crime.
But Ms Hill said she only learned the departments were sharing information in the last two months, after the ministry approached the firm asking for more information about three prison inmates - and abuse complainants - to pass on to police.
"They [the inmates] were very clear that they did not want to speak to the police.
"That's their decision and their decision alone to make.
"And they're really concerned that a major government department doesn't have the basic respect to ask them first."
Ms Hill said state care abuse allegations in general came from very vulnerable people, and many from prisoners who feared being labelled as "narcs" if it became known they'd been talking to the police, even if it was about a private matter.
She said she had seen ministry advice that it had passed 354 state abuse allegations on to the police.
Many allegations have sat with the ministry for years - in one of the three cases being taken to the Privacy Commission, the claims are a decade old, she said.
"This is a mass disclosure of information, not a specific disclosure that has been triggered by specific concerns.
"The disclosure comes years after some of the information will have been received by the ministry - so there is clearly no urgency... [and] the ministry have other means of investigating these allegations - it is likely it still employs some of the people described by our clients."
The ministry issued a brief statement referring RNZ to its website, which says: "The ministry has an obligation to protect children and vulnerable members of the community from criminal behaviour.
"As part of fulfilling this obligation and in supporting the government's desire to hold criminal offenders accountable for their actions, the ministry reports allegations of abuse to the New Zealand Police ... The police will then decide if they will carry out an investigation of any alleged criminal offending."
The ministry did not confirm how many historical cases have been referred to police.
It said that a related matter was before the courts, so it would not make further comment.