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 report 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. THE BLOTTER RECOMMENDS BlotterMI5: Teen Al Qaeda Recruits, Russian Spies Target Britain Blotter Sneaky Sandals Could Be Next Terror Tool Photos Explosive Footwear Blotter New U.S. Alert for Shoe Bombers Click Here for Full Blotter Coverage. 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. "Out of abundance of caution, and for any number of other reasons, raw intelligence is regularly shared within the intelligence and law enforcement communities — even when the value of the information is unknown," said Special Agent Richard Kolko. "In the post-9/11 era, sharing information is our top priority. Al-Qa’ida messaging has clearly stated they intend to attack the U.S. or its interests; however, there is no information to state this is a credible threat. As always, we remind people to remain vigilant and report suspicious activity to authorities." "We have no credible, specific information suggesting an imminent attack," a DHS official said. This post has been updated. Do you have a tip for Brian Ross and the Investigative Team?