Customers must be careful when using their bank cards to prevent being defrauded by "skimmers", Standard Bank Group warned on Thursday.
"Customers are also urged to remain vigilant as the fraudsters' main aim is to access customer funds by stealing information off your card as well as getting your secret PIN," said Itumeleng Monale, Standard Bank director of self service channels, in a statement.
"It is therefore imperative that customers protect their card and PIN information."
Skimming, which is a global problem, usually takes place when fraudsters capture card data on devices similar to those used for legitimate point-of-sale or ATM transactions.
"The industry has been hard hit by this modus operandi, which has been around for years; however an increase in these attacks during the last two years is prevalent due to the availability of high-tech skimming devices in the open market."
The devices fit snugly over the card slot on an ATM and can even include a camera to record the PIN number.
"The main point of compromise still occurs when customers' cards are presented to a third party," Monale said.
"Cards and PIN numbers are harvested by syndicate members when they either distract or observe our customers typing in their PIN numbers.
"The rule of thumb is never to let your card out of your sight and when entering your PIN, to cover the PIN pad," she said.
Customers should also keep their daily withdrawal limit as low as possible to minimise loss. The bank advised customers not to insert their cards into slots that looked as if they had been tampered with. If customers suspect a card had been tampered with, they should immediately stop it.
They should also review their bank statements regularly and should not send emails containing their account number and expiry date.
Keep cards in sight and report lost and stolen cards immediately, the bank advised.