A criminal ring with links to Eastern Europe is behind an ATM skimming scam targeting Sydney bank customers, police believe.

Amid a rise in incidences of ATM skimming since January, New South Wales police have released CCTV footage from central Sydney showing two alleged offenders, described as men of Eastern European appearance.

Footage taken at an ATM on Market Street on March 28 shows two suspected skimmers, both men in their 20s or early 30s, one wearing a navy blue polo shirt and black baseball cap and the second wearing a navy blue, long-sleeved shirt.

Security cameras captured this man at an ATM on Beamish Street at Campsie on March 21, 2014 ( NSW Police )

Police have also released a picture of a man captured by security cameras on Beamish Street in Campsie on March 21, thought to be aged in his late 30s or 40s and also described as being of Eastern European appearance.

More than 40 ATMs in a number of suburbs across Sydney, from Clovelly in the east to Parramatta in Western Sydney, and in the CBD have been targeted by skimmers recently.

Detectives from the Fraud and Cybercrime Squad arrested two foreign nationals, one Hungarian and one Romanian, for allegedly tampering with an ATM on Market Street in Sydney last month.

Both men are before the courts.

ATM skimmers use cameras to steal PINs

Detective Superintendent Arthur Katsogiannis says there are still a number of people out there fitting skimming devices to vulnerable ATMs.

"Our investigation, which has been strongly supported by a number of banks, suggests that the spike in ATM skimming incidents can be attributed to an organised syndicate targeting ATMs in suburbs right across Sydney," he said.

"The skimming devices the group are using are capable of copying card details while a tiny video camera records people entering their personal identification numbers.

"A copy of the compromised card is then created, with all of the capabilities of the original, allowing the group to access the account holders' funds at liberty."

Police said members of the group remained at large and would likely continue targeting ATM users.

"While we have arrested some members of the group, we know there are still a number out there, so cardholders need to exercise caution when using ATMs," Detective Superintendent Katsogiannis said.

"Make sure you carefully cover the hand entering the PIN with your other hand, a newspaper or a magazine.

"It's also important to regularly check your bank account transactions so that if you spot any suspicious withdrawals you can contact your financial institution before more money goes missing."

Anyone who recognises the men are asked to call Crime Stoppers on 1800 333 000.