Confidential information on individual workers' injuries and cost of treatment has been sent in error to more than 2000 businesses, the Accident Compensation Corporation (ACC) admitted tonight.
ACC said it provided businesses around the country with a report on injuries that occurred in their workplace.
The report had two parts, a cover sheet and an attachment which included the name of the individuals, the type of injury they sustained and the cost to date.
About 15,000 businesses received such a report each month.
ACC said in line with standard practice in the public and private sectors, it used an external mail house for a mail-out of this size.
The mail house collated and sent the reports but was not involved with the data in individual reports.
"While the mail house does have measures to ensure that the right attachment goes with the right cover letter, unfortunately a problem has occurred with the January mail-out. The reports have not been collated correctly by the mail house and some 2000 businesses will have received information intended for other organisations, including private information," ACC general manager Keith McLea said.
ACC learnt of the problem today and said it was attempting to get the reports back and to the correct businesses.
"We have also requested a full investigation be done by the mail house and that they review their processes to ensure that this doesn't happen again. We have also contacted the Privacy Commissioner to advise what has happened."
The organisation said it was disappointed in the privacy breach and apologised to individuals and businesses that had been affected.