Online graphic warns of al Qaeda return to NYC

This image provided by the New York Police Department shows a graphic found on al Qaeda Internet forum currently being investigated by police as a terrorist threat. Authorities are trying to identify the source.

(CBS/AP) NEW YORK - A mock movie poster warns al Qaeda wants to return to New York City, but authorities say there's no evidence of an actual threat.

Investigators learned about the online amateur graphic on Monday. The graphic shows the Manhattan skyline at sunset with "Al Qaeda" in bold type followed by "Coming Soon Again in New York."

Al Qaeda has been blamed in the Sept. 11, 2001, terrorist attacks, which destroyed the World Trade Center and killed thousands of people.

New York Police Department spokesman Paul Browne says an overseas, Arab-language Internet site posted the graphic on its "artwork and design" page. He says the NYPD has been monitoring the site.

A law enforcement source told CBS News that indications are the website is based in Indonesia. The site has been used to post messages by individuals sympathetic to al Qaeda. The source said that while the graphic "is not an explicit threat, it is scary."

Another federal law enforcement source told CBS News the graphic wasn't the specific work of al Qaeda but most likely an online jihadist trying to stir the pot.

FBI spokesman J. Peter Donald says the agency takes all threats seriously and "there is no specific or credible threat to New York."