Yahoo! has teamed up with the Nectar loyalty card scheme from Sainsbury's to let online advertisers target consumers based on purchases they make on the high street.
The Customer Connect scheme sees the two companies combine their databases for those shoppers who choose to be included in the initiative to link supermarket spending trends with each consumer's Yahoo! login.
Shoppers will then be shown ads relevant to their supermarket purchases on Yahoo!'s network of websites.
It does not make use of information that could be utilised to identify individuals participating in the scheme. Some 20,000 consumers have already chosen to join the initiative, the Financial Times reports.
About 16.8 million people currently hold a Nectar card, with the retailers linked to the loyalty scheme including Sainsbury's, BP, Debenhams and Homebase.
Figures from comScore suggest that some 23 million people in the UK visit Yahoo!'s web properties, according to paidContent:UK.
Six brands are believed to have signed up to take part in Customer Connect.
Mark Rabe, managing director of Yahoo! UK, says: "For the first time, UK advertisers will have a simple way to track offline sales from online advertising campaigns."
Nectar also allows consumers to collect points when shopping online through its website, offering incentives for purchases made from ecommerce sites such as Amazon, eBay and the Apple Store.
