Thieves have been contacting Doncaster businesses which have had cash cards stolen pretending to be from their banks and asking for the PIN numbers.
Eamonn Larkin, Doncaster's crime prevention officer, said firms in Armthorpe and Bawtry had bank cards stolen and were then contacted by crooks trying to find out the PIN numbers.
They claimed they were from their banks and that attempts had been made to withdraw cash, before asking for the PIN numbers.
Mr Larkin said: "Cards were stolen during sneak-in burglaries at business premises.
"Offenders later rang the complainants claiming to be from the bank issuing the cards.
"They stated that someone was using the cards to try and withdraw money from the account and asked for the PIN.
"Luckily the owners immediately realised that the cards had been stolen and ended the call.
"Please consider the security of your work premises. Take the same security precautions there as you would at home. Restrict access to non-public areas and put your valuables whenever possible in a locked and secure drawer or cupboard.
"Your bank will never ring you and ask for your PIN.
"Anyone phoning or indeed emailing you and asking for your PIN is not from the bank but wants to use the details to access your account and empty it of funds."