ATM scammers have become so sophisticated that it may no longer be good enough to use your hand to hide your PIN number, police warn.
Two foreign nationals - a Hungarian and a Romanian - were arrested last month after allegedly tampering with an ATM in Sydney's CBD.
But police believe others are still out there, fitting skimming devices to vulnerable ATMs.
Police have released security camera pictures of two men wanted for questioning, both of Eastern European appearance and aged in their 20s or 30s.
They say more than 40 ATMs in Sydney suburbs including Mosman, Double Bay, Dural and Parramatta have been targeted since January.
A gang with links to Eastern Europe is believed to be behind the spike.
Arthur Katsogiannis, Commander of the Fraud and Cybercrime Squad, said the criminal group was highly organised and sophisticated and had already bagged more than $100,000 through the scam.
"This type of crime is the choice of criminals in the 21st century," he told reporters in Sydney on Monday.
"With the advent of technology, advancing at an exponential rate, this will be more and more common."
The skimming devices used by the group are capable of copying card details while a tiny video camera records people entering their personal identification numbers.
A copy of the card is then created, allowing the group to access the account holders' funds.
Detective Inspector Matt Craft said the cameras are more sophisticated than what has previously been used by ATM scammers, which were only able to pick-up footage from the top of the keypad. Now, they can pick up different angles.
He urged ATM customers to be more vigilant with covering their hands while they type in their PIN numbers.
"Use your wallet, your purse, a newspaper - something else so that it's covered virtually (all over) and not just the top," he told reporters.
"That's the best way to combat this particular type of crime."
