Sainsbury’s boss Simon Roberts has defended its  decision to sell customers’ Nectar card data, and insisted it was protected “incredibly carefully”.

By selling data to partners including television channels such as Channel 4 and consumer goods manufacturers, advertising can be tailored to specific groups.

Roberts told The Guardian that adverts are now more “relevant” for customers, while also insisting that all data was safe.

He said: “Our retail media platform [works] with suppliers with anonymised customer data, very importantly, we protect our data incredibly carefully.

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“What we want to do at its heart really is provide personalised messaging to customers so from what we hear from customers, they don’t want to be sent lots of marketing and media messages that aren’t relevant to them.

“By understanding customers better, it means we can target our loyalty programmes more effectively.”

It comes as both Sainsbury’s and Tesco are estimated to make £300m a year from selling this data collected through their Nectar and Clubcard loyalty schemes, The Sunday Times reported.

In September, consumer watchdog Which? accused supermarkets including Sainsbury’s and Tesco of opting for “potentially dodgy tactics on loyalty offers” to give the impression that their scheme savings are better than they really are.

Last month, the Competition and Markets Authority (CMA) also expressed concern over the fact that cheaper prices are only available for loyalty card members at some supermarkets.

CMA chief executive Sarah Cardell said “this raises a number of questions,” with a review set to launch in January 2024.

However, Roberts told The Guardian that Nectar discounts are “absolutely genuine great value prices for customers”.

“The vast majority of customers in supermarkets want to use Nectar because it saves them money. If you spend on average £80 pounds this week and use Nectar Prices, you’ll save about £10 on your shop so customers really like that value,” he added.