Police were working with banks and couriers to see if they had noticed any "suspicious behaviour", Blackman said.
He urged them to be "extra vigilant" with customers who may be particularly vulnerable or were withdrawing large sums of money, which "might be an unusual pattern of behaviour for them as a customer".
"The scam involves callers claiming to be from Spark and/or police before convincing victims to withdraw or to transfer tens of thousands of dollars from their bank accounts."
The victims in these matters were almost always contacted initially on their landline phones, Blackman said.
The caller typically claimed they were from Spark, claiming there was a security or internet issue with their computer or router.
At some point in the conservation, the victims were usually told they were the subject of identity theft/fraud through their emails and told they are being transferred to a member of the "Police Cyber Crime Unit", where they are spoken to by a person claiming to be a police officer.
"The victim is then told that police need their assistance to set up a "trap to catch the criminals'.
"They are convinced to withdraw large sums of money – often in the area of $10,000 - $15,000 – and given an address to post the money to or bank account to transfer it to."
Blackman said police were aware of victims being asked to send money to various Auckland addresses, as well as offshore locations in Australia, Japan and Spain.
"A police officer will never ask for your bank details over the phone or ask you to transfer money," he said.
"If you receive a call of this nature, hang up immediately. There is no legitimate reason for a stranger to need to put money into your account.
"If you are ever asked, do not accept any money and contact police."
Blackman urged anyone who believed they were a victim of a scam, or knew someone who had handed over money, to contact their local police station with "urgency".
Those who received calls from suspected scammers were also urged to hang up immediately.
