US firm Nomi failed to notify customers of tracking according to the FTC.
Nomi Technologies has reached a settlement with the US FTC regarding its tracking of retail store customers.
This, according to the Federal Trade Commission, implied that notification would be given to customers, which it did not do.
The agency stated that Nomi collected information from around 9 million mobile devices for the first nine months of 2013.
Jessica Rich, director of the FTC’s Bureau of Consumer Protection, said: "It’s vital that companies keep their privacy promises to consumers when working with emerging technologies, just as it is in any other context."
"If you tell a consumer that they will have choices about their privacy, you should make sure all of those choices are actually available to them."
The tracking of customers is one that is being use more frequently by retail stores as they look to optimise store layouts and product placement.
Although Nomi has escaped a fine, this case will act as a warning to others in this industry to be careful with the wording of privacy policies and making sure they are fully implemented.
The information that Nomi collected includes the MAC addresses of store customers’ mobile devices, this information is hashed before storage.
According to the FTC complain, Nomi also tracked consumers outside of the store and collected data on device type, date, time andother information.