"They're doing a difficult job in one of New Zealand's hardest prisons. They've been assaulted at work.
"They quite rightly want people to be held to account. They shouldn't be persecuted in the process."
Waitemata Police District Commander Superintendent Tusha Penny said the documents were evidence in a forthcoming trial relating to the assaults.
"We are discussing appropriate security measures for the affected staff members. However, we will not discuss these measures publicly.
"We have expressed our deep regret to Corrections that this error has occurred."
She said police became aware of the issue last week, and have launched an internal inquiry.
"The material was being disclosed as part of the routine prosecution process when the error has occurred.
"The disclosure has occurred as a result of human error. Police are working closely with Corrections on this matter."
The Corrections Association is seeking assurances the guards will be kept safe, and the incident will not happen again.
Whitley said it is not the first time the safety of the guards has been jeopardised, but it should be the last.
"I know the police have apologised, and it's right that they apologise.
"Unfortunately this is not the only time this has happened, and we're seeking an assurance from them that it never happens again."