STYLETHREAD -- LET'S TALK SHOP!

The FBI is warning that al Qaeda may be preparing a series of holiday attacks on U.S. shopping malls in Los Angeles and Chicago, according to an intelligence bulletin distributed to law enforcement authorities across the country this morning. (Click here for full text.)

The alert said al Qaeda "hoped to disrupt the U.S. economy and has been planning the attack for the past two years."

Law enforcement officials tell ABCNews.com that the FBI received the information in late September and declassified it yesterday for wide distribution.

The alert, like similar FBI and Department of Homeland Security terror alerts issued over the past five years at holiday times, raised questions about the credibility of the information.

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The bulletin acknowledges that U.S. intelligence officers are uncertain as to whether the information is real, and intelligence officers say there is a concern that it could be "disinformation."

Law enforcement officials at three different agencies told ABCNews.com the FBI alert was based on a source who has proved reliable in the past.

The source reportedly had only "indirect access" to al Qaeda and word of the actual threat came to U.S. intelligence officers "through a lengthy chain" of contacts.

With the shopping season approaching, however, the FBI officials decided it was necessary to share the information.

For the past few years, jihadist chat rooms have regularly posted comments from anonymous individuals who have suggested or boasted about similar plans to attack such soft targets as shopping malls.