The Corrections Association's national president, Alan Whitley, is concerned about a privacy breach by the NZ Police that put the personal details of six prison guards in the hands of violent inmates.

Six Corrections officers who are key witnesses in an upcoming trial have grave concerns for their safety after files containing their personal information were found in a gang member's cell.

The officers were assaulted in October at the maximum security Auckland Prison in Paremoremo, north Auckland, and suffered a range of injuries including stab wounds from weapons made from metal television brackets.

One file was found in the cell of Josh Masters, the leader of the Killer Beez gang. Masters is not facing charges in relation to the attack. Another file was found in the cell of a Black Power member.

DAVID WHITE/STUFF The officers were injured in an attack at Auckland Prison in October.

The information in the files included staff names, addresses and phone numbers.

READ MORE: Five prisoners assaulted three Paremoremo Prison staff

Alan Whitley, president of the Corrections Association, said while prisoners had the rights to view files, if they had charges against them, it was normal procedure for police to blank out personal information.

"This isn't the first time this has happened and we're asking for the assurance from police that it won't happen again," Whitley said.

"We don't want a repeat of this, it sows the seed for Corrections staff is they're involved in something like this to question if their privacy will be protected. It could make them have second thoughts about reporting incidents similar to this one," Whitley said.

Police Superintendent Tusha Penny said the breach was a result of human error.

"We have expressed our deep regret to Corrections that this error has occurred," Penny said.

Whitley said the staff involved were being taken care of and were being provided protection.