NEW YORK (TheStreet) -- Apple (AAPL) - Get Report reportedly is telling software developers to stop using a feature that allows them to track users of iPhones and iPads.

The move may be in reaction to privacy concerns.

Apple told developers it would phase out access to the unique device identifier, or UDID, on devices that use the iOS operating system, technology blog TechCrunch reported Friday.

The blog said it had obtained a copy of a recent update to the documentation for iOS 5 that had been distributed to developers. Apple says it will release the iOS 5 version of the operating system this fall.

App publishers had used the UDID to track the way people used apps for iPhones and iPads.

Software developers will now have to create their own unique identifiers to track users, TechCrunch noted.

The move could have major implications for the app ecosystem, particularly mobile ad networks, game networks and apps that rely on the UDID to identify users, the technology blog also noted.

Shares of Apple closed Friday down $10.02 at $356.03.

This article was written by a staff member of TheStreet.