The Public Service Association says an investigation into who leaked MFAT documents to the Labour Party was a waste of time.
The State Services Commission asked Paula Rebstock to conduct the inquiry after the Government became outraged at information being leaked to Labour's foreign affairs spokesperson, Phil Goff.
The report found the source was most likely a temporary State Services Commission staff member who used to work for the Labour Party.
PSA national secretary Brenda Pilott said not only was a lot of time and money spent on the inquiry, but many people were unnecessarily put through an interrogation process.
She said the inquiry created a climate of fear among the public servants involved.
States Services Minister Jonathan Coleman defended the cost of the report.
Dr Coleman said the central issue is the integrity of the public service and that finding lies at the heart of the report's conclusions.