Consumers are being urged to regularly check bank statements for any unusual activity as cyber criminals will use the major event in the retail calendar to seize money from unsuspecting shoppers, comparethemarket said.

The warning follows recent estimates that 4.5 million people have been forced to cancel credit and debit cards due to online fraud in the past year.

Analysis of previous online sales figures by the comparison site found shoppers spend ten times the usual amount over the two discount shopping days as they look to cash in on the sales.

A survey of 2,000 consumers found nearly half plan to do their Christmas shopping online, equating to 23 million adults in the UK.

Simon McCulloch, director at comparethemarket, said: “Black Friday and Cyber Monday is a major event in the retail calendar. It is also a salmon run for cyber criminals, who will try to seize money from unsuspecting shoppers and retail outlets. Consumers should regularly check bank statements for any unusual activity, as cyber criminals often make small but regular thefts which are harder to spot than larger one-off purchases.”

How to stay safe:

1. Consider paying for all purchases with your credit card, which will offer additional protection under Section 75 of the Consumer Credit Act, so that if someone steals your ID then your credit card provider will compensate you for any loss
2. Register your cards with Verified by Visa or MasterCard SecureCode as this protects your card against unauthorised use
3. Always check the website addresswhich should begin https:// rather than http://”