New York, Nov.28 : New York City police have stepped up patrols in the city's subways and trains after the federal government warned of a potential Al Qaeda attack during the holidays.
The potential threat - described in an internal FBI memo as "plausible but unsubstantiated" - does not extend beyond the New York City area, sources told FOX News.
NYPD spokesman Paul Browne was quoted by Fox News as saying that the police have received the report and have "deployed additional resources in the mass transit system."
A person briefed on the matter, said the threat might also be directed at the passenger rail lines running through New York, such as Amtrak and the Long Island Rail Road.
While law enforcement stepped up patrols around subways and trains, many commuters around the city were unfazed by the news and had not even heard of the threat.
The vulnerability of the city's tightly packed passenger trains and subway cars has long been a source of concern for cops - and target for would-be terrorists. The city has more than 450 subway stations that handle millions of commuters every day.
Bruce McIndoe, president of iJET Intelligent Risk Systems, which advises companies on travel safety, said transportation is always a "hot" area for terror concerns, but individual warnings don't mean terrorists have the capability to pull off such an attack.
FBI spokesman Richard Kolko confirmed only that his agency and the Homeland Security Department issued a bulletin Tuesday night to state and local authorities, and the information is being reviewed.