Apple used freshly deployed iBeacon sensors to virtually -- and personally -- accompany iPhone, iPad or iPod-toting shoppers through its US stores on Friday.

Code woven into Apple's newest iOS mobile operating software lets the sensors tell when one of the California company's gadgets is nearby in-store and then fires off messages about deals, products or other relevant information to draw a potential buyer in.

For example, iBeacon could chime in about iPads when someone is checking out the Apple tablets, or weigh in on iPhone covers or ear buds when a shopper pauses at an accessories display.

The sensors "push" information to shoppers' iPads, iPhones or iPods using wireless Bluetooth technology.

"We're really excited about what iOS developers will be able to do with iBeacon, a technology we introduced with iOS 7 that uses Bluetooth Low Energy and geofencing to provide apps a whole new level of micro-location awareness, such as trail markers in a park, exhibits in a museum, or product displays in stores," Apple said in a statement to the press.

Apple maintained that the system gathers no data back from devices and merely provides information at seemingly appropriate moments in its stores.

Retailers are increasingly gathering data from smartphone users in shops and tracking their locations and buying habits in an effort to boost sales and efficiencies.

This practice is drawing scrutiny from privacy activists as the market for this technology shows sizzling growth.

"I can't even count the number of startups in this field," said Leslie Hand, retail analyst for International Data Corp.

Hand said it is difficult to estimate the value of this market because it is so new, but that retailers are anxious to use smartphone data "so they have as much information about the customers in the store as they do about the customers shopping online."

By tracking users' smartphones and their unique identifiers, retailers can tell how often a customer visits, how much time they spend in a location and other data.

With this, retailers "can better understand customer-buying behavior to market better, and possibly make an offer to them," Hand told AFP in an earlier interview.

But this type of tracking -- at a time when Americans are wary of government surveillance -- has raised the hackles of a number of consumer privacy groups and lawmakers.