The government says it is disappointed by yet another privacy breach at the Earthquake Commission, with letters sent to the wrong claimants.
The latest blunder saw about 260 customers' details sent to the wrong person when letters were incorrectly enveloped.
The letters were acknowledgment that EQC had received claims and contained customers' addresses, phone numbers, insurance company and damage details.
The letter was supposed to be double-sided, but was instead printed as two pages, and each page was put into a different envelope, a spokeswoman told NZ Newswire.
EQC chief executive Ian Simpson has called for an investigation, but said the issue again appeared to be human error.
"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," he said.
Earthquake Recovery Minister Gerry Brownlee says the error is regrettable, but EQC is handling it appropriately.
"It appears to be a human error. I guess when they're dealing with that level of correspondence, things can happen," he told media.
The latest breach follows two more serious breaches in March.
Human error saw the details of 83,000 Canterbury earthquake claims, including addresses and repair values, were mistakenly emailed by an EQC manager to Christchurch man Bryan Staples.
EQC then shut its email and data exchange systems a week later after it sent the bank account details of 2000 people to one of its claimants in a spreadsheet attached to an email.
The spreadsheet included details of EQC cheques totalling $23 million.
A review of 215 government computer systems released in June found 12 government agencies had computer security weaknesses, including EQC, the Ministry of Justice, the Ministry of Social Development and the Department of Corrections.