The bank's survey of 1300 customers suggests scams were ubiquitous, with 87 percent saying they had received a suspicious email, text or phone call in the past six months, and 49 percent said it was harder to tell if these messages were fraudulent.
Westpac NZ head of financial crime Mark Coxhead told RNZ the findings were not all that surprising.
"It was perhaps a little higher than what I had been expecting, but anecdotally this was backing up what we were hearing from our customers and even what you are just hearing in a social environment."
Coxhead was unable to reveal the total financial loss its customers had suffered in the past year to scams but said the number had doubled.
The techniques scammers were employing are becoming more advanced, he said, challenging the notion that it was just older people who were vulnerable to scams.
"Traditionally, it used to be the email from the Nigerian Prince or a lawyer in another country [saying] that you've got a deceased relative wanting your details."
But increasingly, impersonation scams, in which a person pretended to be a bank, a credit card company or a government department were on the rise, he said.
Scammers were also making use of personal information they had gleaned online to make themselves appear more legitimate, Coxhead said.
He said they would call from a phone number that appears legitimate, making it hard for customers to know just who they were talking to.
The bank released a phone recording of a fraudster pretending to be from the "Westpac Fraud Team" when speaking to one of its customers.
The scammer already possessed the customer's name, phone number and credit card details.
They tried to build trust and elicit further information by telling the customer that their card was being used for suspicious transactions in Mexico.
The scammer sends then the customer a text message with a code which they claim is to authorise the card's cancellation, when in fact it is a verification code for an online purchase.
Unwittingly, the customer provides the code to the scammer over the phone.
"Fortunately, in this case another fraud detection system blocked the transaction, so the scam was unsuccessful," Coxhead said.
He said there were a number of red flags people should look out for, such as unsolicited phone calls, a sense of urgency from the caller and unusual payment methods.
"Be vigilant, if it feels too good to be true, it probably is.
"Never give anyone your pin or codes and if they have come through on the phone just hang up."
