The Earthquake Commission has admitted to another breach of privacy after information on up to 260 claimants was sent to the wrong customers.
Its chief executive Ian Simpson has launched an inquiry into how the information ended up on a letter that was sent to some clients.
One side of the letter had the correct information for the recipient, but the second side of the page had the address, phone number, insurance company and the damage reported by a different claimant.
It contained no financial information.
The letter was collated manually in Wellington and the error occurred during the collation process. Mr Simpson said at this stage it appeared to be human error.
EQC would be contacting the letter recipients today to explain what happened and apologise, he said.
"EQC has made a concerted effort to make sure customer information is as secure as possible and increased the level of checking we do, but regrettably this mistake has still occurred and I can only apologise to those affected.''
The privacy breach is the third this year after one claimant received an email with an attached spreadsheet with 2200 names, stopped cheque details and claim amounts worth about $23 million. Another email was mistakenly sent to a former EQC contractor, Bryan Staples, with claim status and private details of 83,000 claimants, covering 98,000 claims.