A spokesman for the ABC shop at Castle Towers said there was an almost immediate effect when news of the scam broke in mid-January customers stopped entering PINs and elected to pay by credit and sign for purchases.

``We've seen an immediate stop on card-users entering PINs,'' the spokesman said.

``That puts more pressure on my staff because the security of their transactions depends on my staff checking signatures.''

NSW Police Strike Force Wigg continues to investigate the use of skimming devices which covertly capture card data which is used to withdraw funds from an account.

Police estimate more than $50million has been stolen from more than 100 accounts in the past 12 months and six people have been arrested.

Money is taken when eftpos terminals are stolen during armed robberies and modified to copy information from magnetic strips on debit and credit cards.

The modified terminals are then put back into a different store, including busy fast-food outlets (understood to include various McDonald's), convenience stores and clothing retailers and the captured information (including PINs) is used to make unauthorised withdrawals from accounts.

Retailers say there is a heightened sense of awareness about protecting personal details.

The manager of the stationery shop Kikki.K, Mel Coghlan, said there had been a marked increase in customers covering the keypad when entering their PINs.

``In the past people used to just enter their PINs and people behind them could see it but now they're covering up the screen,'' she said. ``We tell the girls to look away. There aren't quite as many people using eftpos and an increase in those using credit but that might just be a trend as a lot of people use credit cards in our shop.''

Many customers in Castle Hill said they were withdrawing cash from their bank accounts to use instead of paying by electronic transaction (see page 11).

Police have warned customers to check transactions regularly and report anything unauthorised to their banks, change their PINs and sign for purchases instead of entering PINs.