Black Friday is fast becoming Black Fraud Day with the discount period now “prime time” for scammers, according to Britain’s cybersecurity chief, who said criminals were using artificial intelligence to trick shoppers.

With online criminals taking advantage of an eagerness to save money amid the cost of living crisis, last Christmas people in the UK were scammed out of more than £11.5m, figures show, almost £1m more than in the same period in 2022. Fake clothing or high-end tech listings on social media were among the common ploys used to dupe people.

The festive season had become “prime time for cybercriminals” as consumers hunted for deals, said Richard Horne, the chief executive of GCHQ’s National Cyber Security Centre (NCSC). Fraudsters were “targeting bargain hunters with increasingly sophisticated scams, sometimes crafted using AI, making them harder to detect”, he added.

More than 16,000 reports of online shopping fraud were recorded between November 2023 and January 2024, with each victim losing £695 on average.

Meanwhile, 7,168 reports (43%) made to Action Fraud, Britain’s scam reporting centre, mentioned a social media platform. Online marketplaces were mentioned in 18.9% of reports.

The figures, which were analysed by the National Fraud Intelligence Bureau, also showed people aged 30-39 accounted for the largest proportion of those who submitted a report (23%), closely followed by 40- to49-year-olds (20%). The average age of victims was 42.

“Never feel pressured into buying anything online,” said Adam Mercer, the deputy director of Action Fraud. “Creating a false sense of urgency is a tell-tale sign of a fraudster.”

He added: “Whether you are shopping on online marketplaces, social media or retailers, avoid bank transfers if you can, and use a credit card as it can provide more protection if anything goes wrong.”

Black Friday started out as a single day of discounts, but with promotions now running for several weeks it has become the biggest shopping event of the year during which billions of pounds are spent.

This year, average spending in the November sales is expected to hit £365 per shopper, up from £300 in 2023. This is despite four-fifths of people (82%) saying they are concerned about price increases for essentials such as food and energy, according to a study by Boston Consulting Group.

With so much money at stake, scammers appear to be redoubling their efforts. The telecoms company Three said its customers were already reporting an increase in messages from fraudsters. Close to 3,500 scams a day were reported to Three during the Black Friday period last year. Since January, the volume of scam messages reported each month was 170,000 higher than in 2023, it said.

To fend off scammers, the NCSC, which is launching a public awareness campaign on Monday, advises consumers to set up two-step verification, which provides an extra layer of protection and means that even if a criminal knows your password, they still will not be able access your accounts. Other advice is not to click on any links, and to research the company or seller by looking at reviews on trusted review sites.