Customers of a "large-scale" Auckland retailer have been targeted by a card-skimming scam, with hundreds of thousands stolen and all the major banks hit.
Police have now launched an investigation, but would not comment on the identity of the retailer, which they said was co-operating.
Christchurch customer Charlotte Helm was contacted by her bank after two large sums of money were withdrawn from her account from the UK.
Helm was told details from her card had been stolen or scanned while she had made a transaction.
Scammers then utilised those details to create duplicate cards, which they used to withdraw cash from overseas ATMs.
She said she was upset to hear her accounts had been compromised.
"I was fine in the end because we got our money back, but at the same time, how the hell does this even happen?
"I really wanted to know who it was that had the security breach, and how on earth my bank card was compromised. That frustrates me - as a customer I think we should be entitled to know that stuff."
The skim had occurred while she was on holiday in Auckland
Helm was reimbursed by the bank last week, and she was happy with the bank's response.
Detective Senior Seargent Aaron Pascoe confirmed police had launched an investigation.
"Police have received a complaint from a bank about card skimming offending that has occurred at some business premises in Auckland," he said.
He said the offending had involved all the major banks, and the retailer involved was assisting the investigation.
Kiwibank communications manager Bruce Thompson said the retailer skimming incident had affected more than 2500 customers, and the bank took immediate action to protect accounts.
He explained a skimming device would scan details of the card, send them overseas, and duplicate cards would be made. Then an orchestrated attempt would be made to remove money from the accounts."
He said there was "nothing customers could have done to protect themselves, and there was nothing they did wrong."
An ASB spokesperson said the bank had "identified a recent trend of suspicious activity in relation to a non-ASB merchant. This is a continuation of the compromised activity from another bank's merchant that was detected two weeks ago."
She said ASB had already cancelled some customer cards.
This news follows revelations last month that cards from a number of New Zealand banks had been compromised after "skimming" devices were installed on inner city Auckland ATMs.
Bank representatives said ATMs were more frequently targeted by skimmers, and for a retailer to be compromised was less common.
Police and banks would not comment on how retailers could protect themselves from skimmers.