More than 12 victims have come forward to police over the past month after their card details and PINs were extracted by card skimming devices clandestinely attached to ATMs around the city.

Police say the card skimmers have predominantly been used on ATMs in Civic and Woden, but are warning that many victims may not have yet realised their money has been taken.

The skimmers work by extracting card data from the card's magnetic strip, while a tiny video camera records the victims keying in their PIN.

The device is later removed, and the data and video recordings downloaded.

Acting detective sergeant Rachel Batterham said the victims each had about $1000 taken.

''This is a sophisticated and methodical way of obtaining funds from someone's account,'' Detective Sergeant Batterham said.

''It's also risky in the fact that someone has to physically attach the device to an ATM, and come back at a later time to remove it and download those details,'' she said.

Similar devices have been used in Victoria and Queensland recently, and ACT Policing is liaising with authorities in those states.

Queensland police found a number of highly sophisticated devices in Brisbane's Queen Street Mall last week, designed to look like the green-coloured anti-skimming devices that are fitted to many ATMs.

Victoria Police also arrested two Malaysians over an international card skimming operation in Melbourne earlier this month.

Detective Sergeant Batterham said it was possible that a single skimming device may have been used at a number of different ATMs in Canberra.

CCTV footage will be the key in helping police catch the offenders, and police say they will examine footage to try and find the person responsible for fitting the devices.

Police have urged people to check their accounts for unauthorised transactions.

They are also warning Canberrans to check ATMs carefully before using them, looking for any irregularities or suspicious devices.

Customers are also urged to cover their hands as they enter their PIN.