The teller had been busy on the phone and appeared distracted.
The individual did not think anything untoward about the envelope and opened it when he got home; only to discover that it contained confidential documents he was not meant to see.
He handed the documents to a friend. "As soon as I saw it, I thought 'this is another privacy breach'," the second man said, referring to similar events with ACC clients receiving confidential information in the mail.
Neither individual wanted to be named, but both were worried at the carelessness of the breach.
"This sort of thing shouldn't happen."
Kiwi Bank responded this morning saying that the privacy of their customers was "very important" and they regarded the incident seriously.
"We are investigating the situation and we will take the appropriate steps to contact the affected customers to let them know what has happened, and conduct a review of the processes in the Greymouth branch to ensure this situation does not happen again," a spokesman said.