The data protection watchdog has told Sky News that consumers need to be increasingly wary of what companies do with credit card details given over the phone or online.
The warning from the Information Commissioner's Office (ICO) comes as record numbers use internet and telephone shopping services ahead of Christmas.
ICO head of strategic liaison Jonathan Bamford told Sky News: "Although Christmas is the season for giving, be very, very careful when you give your personal details.
"It's really valuable - treat it like your money."
He added: "You should be very wary of who you are dealing with in an online transaction, if you are not confident with the organisation don't proceed with it."
Further concerns have been raised by the increasing use of audio recording of customers' telephone calls by companies.
While many firms tape calls for "training and quality purposes", recordings which contain bank or card details are at risk of fraudulent use if proper precautions are not taken.
"Organisations that do use audio recordings need to make sure they don't hold those for any longer than they need to really verify the transaction," Mr Bamford said.
"Data protection law requires them to get rid of information when they don't need it any longer and that applies to audio recordings, along with any other personal details, which may have credit card information."
Banks have long used audio recordings to pursue internal fraud investigations but retail firms are using the audio technology too.
The watchdog can impose penalties of up to £500,000 data protection breaches by organisations.
Greater Manchester Police was also fined £120,000 after an unencrypted memory stick was stolen that contained details of more than 1,000 people with links to serious crime investigations.
"If there are real concerns about what happens to our information we have rights of access to find out about that," Mr Bamford told Sky.
"If the worst comes to the worst, the Information Commissioner has powers to make sure companies look after our information properly."
Corporate solicitor Maung Aye, of Mackrell Turner Garrett, told Sky News: "Companies should take their data protection obligations very seriously.
"There are not only substantial financial penalties which the Information Commissioner can impose but a number of other potential ramifications including adverse publicity affecting the company’s image, brand and reputation and even criminal liability for directors which could ultimately result in imprisonment."
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