The Federal Bureau of Investigation (FBI) has disputed a computer hacker group's claim that it stole personal identification data on millions of Apple device owners from an FBI agent's laptop.
FBI officials said the bureau never asked for and never possessed the database that the group, which calls itself AntiSec, is posting on a website.
The group has released a link to a database of more than one million unique identification numbers for Apple devices, which could include iPhones and iPads.
In the posting, AntiSec said the original file "contained around 12,000,000 devices" and that "we decided a million would be enough to release".
The group said it "trimmed out other personal data as, full names, cell numbers, addresses, zipcodes, etc".
Officials at the FBI, however, said they could not verify the validity of the data that AntiSec released.
Federal officials also warned that computer users should be careful when clicking on such links because they sometimes may contain malware that can infect computers.
It also raises question over why the FBI had held the details of consumers of Apple products.
Apple also did not immediately respond to a request for comment.
The hacker group said it posted the information to draw attention to Apple's practices which allow users to be tracked.
"We never liked the concept of UDIDs since the beginning indeed. Really bad decision from Apple," it said.
Apple assigns unique device identification numbers (UDIDs), a string of numbers and letters to all of its devices. The numbers let iTunes and application developers know which device is running which apps.
As an example, the numbers allow game developers to keep track of users' high scores.
Besides the identification numbers, the information posted by AntiSec has the name that a person chooses to name their device and a description of whether the device is an iPhone, iPad or iPod Touch.
If linked with other information such as a name or address, the numbers could be used as a way to get at other more sensitive data. But knowing the number doesn't enable the FBI to track or eavesdrop on people.