New Zealand banks are investigating complaints from at least 60 customers who say money has been taken from their accounts over Easter.
It appears money has been removed in Canada from New Zealand accounts.
The banks say at this stage it is too early to say how the potential fraud was carried out, or how much money has been taken.
About 30 customers at each of BNZ and Westpac have reported fraudulent transactions.
ASB and Kiwibank are also investigating but cannot say how many of their customers have been affected.
ASB says it has noted an increase in skimming scams over the past few days, which it says has affected all banks.
A BNZ spokesperson says the banks are working together to see if there are common elements to the actions.
ANZ-National couldn't be reached for comment.