An inquiry has been launched after the discovery of the names and personal details of more than 500 children who were state wards on open display at Archives NZ.
The details sitting in public view included personal family and fostering records, behavioural assessments, medical and psychiatric details and records of alleged child and youth criminal offending.
Oranga Tamariki has shut down access to all of its records at Archives NZ after being alerted to the privacy breach by the Herald and is reviewing its entire collection.
The discovery has prompted Archives NZ to tell other state sector chief executives to check files their agencies have put into storage in case more private material is publicly accessible.
The Herald found the material while investigating the background to the Royal Commission into state and faith-based abuse .
• Prime Minister Jacinda Ardern unveils inquiry into state care abuse
• Editorial: Victims will be heard in major inquiry
• Mongrel Mob member Harry Tam's role in state abuse inquiry being investigated
• Bishop of Dunedin eyes full reveal of sexual abuse claims
Using the Archives NZ search system Archway , the Herald searched for records belonging to former state institutions which housed the estimated our 100,000 state wards.
While most institutions were coded with a "red" restricted access, others were set with "green" open access rights.
The largest collection of files related to Hokio Boys' School and Kohitere Boys' Training Centre, both north of Wellington and on the outskirts of Levin.
The Herald had collected copies of documents on the files in November, February and July yet hadn't analysed and examined the documents until this month, at which point Archives NZ was alerted.
Exclusive: Risk to women at Mason Clinic 'incredibly concerning'
Twin investigations into care, deaths of intellectually disabled
The files offered an insight into how the institutions operated through general correspondence and record-keeping.
But large tracts of documents also included personal details about individuals who were raised in the homes.
It comes after Cabinet told social agencies, through State Services minister Chris Hipkins, to identify records relevant to the Royal Commission into abuse at faith-based and state institutions so they could be made available to the inquiry.
The Herald contacted former state wards whose details were in the files.
Tyrone Marks, 59, who sits on the commission's Survivor's Advisory Group, said it was a clear "breach of confidentiality".
Marks, whose experience of state care included sexual abuse, electrocution as therapy and medication for behaviour, said: "They drugged and [abused] us. The way they're acting at the moment, they're still trying to do the same."
Greg Armishaw, who went into state care aged 10, said the files should be covered in "red tape" to signal they could not be accessed.
Now 61, he said he wasn't ashamed of his background but did not believe "Joe Bloggs should be able to go to Archives and look at what happened way back then".
Martyka Brandt, 60, said there were former state wards who felt shame over what they endured at Lake Alice psychiatric hospital and would hate to think any information about that was not protected.
"You had your privacy taken away when you were young and now you're older, it's still happening."
Oranga Tamariki's deputy chief executive of corporate services Matt Winter said: "In partnership with Archives we have immediately moved to find out how far this historical issue may reach.
"As Archives holds millions of records, many of them paper based, this is a task that will require considerable effort but we are already looking at possible approaches to undertake this."
Winter said the files were sent to Archives NZ by the former Department of Social Welfare 30 years ago, prior to the Public Records Act and Privacy Act.
"At the time, the approach to privacy was different. Today this kind of information would be reviewed upon transfer to Archives and restrictions placed on the information as appropriate."
Winter said Oranga Tamariki was working with Archives NZ to assess which records posed an issue and how they should be classified.
It was also trying to establish who had accessed the information, with preliminary inquiries showing government officials were the only parties to have done so - prior to the Herald - although it appeared had not raised the issue.
"The concerns and welfare of the people affected is our top priority and we understand this news may be extremely distressing for those affected. We will continue our work to determine any further action that is required."
Winter said Oranga Tamariki had asked Archives NZ to restrict access to all its files while it worked out the right access levels. Oranga Tamariki was also seeking guidance from the Privacy Commissioner.
A spokesman for Archives NZ access to the records had been restricted "to ensure that no one else accesses the records" until Oranga Tamariki had reassessed the status of the files.
He said the Herald's identification of private material in the open had led Archives NZ to contact government agencies with similar information "to identify any that may need their access reclassified".
"We have provided those agencies with further guidance and are assisting them in any way we can to progress the process."
The default access to files was "open" unless agencies provided reasons they should be restricted.
"Our current advice to agencies is that for material considered to be highly sensitive for reasons of personal privacy, a restriction of 100 years from the date of file closure should be applied."
He said the files seen by the Herald were transferred in 1989, prior to new systems which came with the passing of the Public Records Act in 2005, which now required agencies to consult with the Chief Archivist.
Privacy Commissioner John Edwards said he had been briefed and believed Oranga Tamariki and Archives NZ were taking the matter seriously.
He said he was "very concerned" over the "open access to some of the sensitive information".
"Oranga Tamariki has told me it is working through the files in question to identify and notify affected individuals."
He said Archives NZ had told him chief executives across government would be told and asked to consider if they had historical files with "similarly inappropriate open settings".
In total, Archives NZ held more than seven million files from government agencies in four depots across the country.