Anonymous affiliate "AntiSec" posted a file on the Internet on Monday that it said contained more than 1 million of the Apple numbers. AntiSec said it had taken them from a Federal Bureau of Investigation agent's laptop in March.

"At this time there is no evidence indicating that an FBI laptop was compromised or that the FBI either sought or obtained this data," an FBI spokesman said in a statement.

Apple representatives were not immediately available to comment.

The Apple numbers, called unique device identifiers or UDIDs, are a sequence of letters and numbers assigned to Apple products, such as iPhones or iPads. Many web-based mobile applications and gaming networks use UDIDs to identify users.

In an Internet post explaining the data dump, AntiSec said it removed personal data associated with the UDIDs, such as consumers' names and telephone numbers.

AntiSec said it breached FBI agent Christopher Stangl's PC by exploiting a flaw in the computer's Java software. The group said it downloaded a list from Stangl's computer that was found to contain UDIDs for 12,367,232 Apple devices.

Stangl did not immediately respond to a request for comment.

"If AntiSec and related folks were doing that kind of attack, this would be an upping of the game," said Marc Maiffret, chief technology officer of security firm BeyondTrust.

That said, the data dump itself, while serious, would not prove to be very damaging to consumer privacy, Maiffret added.

"It is not something that is going to allow hackers to break into peoples' iPhones," he said, adding that the UDIDs appeared to be genuine.

Anonymous and other loosely affiliated hacking groups have taken credit for carrying out attacks against the CIA, Britain's Serious Organized Crime Agency, Japan's Sony Corp, Mexican government websites and the national police in Ireland. Other victims included Rupert Murdoch's UK newspaper arm News International, Fox Broadcasting and Sony Pictures Entertainment.

Authorities have been attempting to beat back the intrusions and have arrested a number of the groups' key players.

(Additional reporting by Poornima Gupta. Editing by Andre Grenon)

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