A subsidiary company of Queenstown's district council is refusing to discuss a privacy breach involving the details of thousands of local complaints.
Lakes Environmental has confirmed a staff member accidently emailed a list showing every complaint it has received since 1993 to a member of the public.
The register contained the names and addresses of the complainants as well as details of their complaints.
The Queenstown man received the register several weeks ago, but the mistake only came to light after the man sent the list to the Mountain Scene newspaper this week.
In a statement, Lakes Environmental says it is contacting everyone on the register to apologise and reassure them it has reviewed its systems.
The council-controlled organisation will not discuss what changes it is making to stop the problem recurring.
The agency is being disbanded and merged back into the Queenstown Lakes District Council in July.
Wellington privacy lawyer John Edwards told Radio New Zealand's Checkpoint programme on Friday many publicised releases of personal information have been mainly of names and address, but this one could be more significant.
Mr Edwards says the agency has law enforcement functions including to look out for dangerous dogs and toxic waste dumping, and people ring up on the understanding of anonymity.
The council needs to reassure the public that its systems are secure, he says.