Terror plot against NY subways uncovered

Extra police have been stationed around major transport hubs in the city, after the FBI revealed the threat was "plausible but unsubstantiated".

The FBI recieved "uncorroborated by plausible information that al-Qaeda may have discussed a target at the transit system in New York City," Department of Homeland Security spokeswoman Amy Kudwa said.

The report indicates that al-Qaeda terrorists had spoken of "the use of suicide bombers or explosives placed on subway/passenger rail systems".

"We have no specific details to confirm that this plot has developed beyond aspirational planning, but we are issuing this warning out of concern that such an attack could possibly be conducted during the forthcoming holiday season," the warning says.

While federal agencies regularly issue all sorts of advisory warnings, the language of this one is particularly blunt.

'Increased security'

Intelligence and homeland security officials were working with local authorities to try to corroborate the information "and will continue to investigate every possible lead," an internal memo states.

Department of Homeland Security spokesman Russ Knocke said the warning was issued "out of an abundance of caution going into this holiday season."

No changes are being made to the nation's threat level, or for transit systems.

"However, transit passengers in larger metropolitan areas like New York may see an increased security presence in the coming days," Knocke said.

"This includes uniformed and plain-clothed behaviour detection officers, federal air marshals, canine teams and security inspectors."

ABC television quoted unnamed law enforcement sources as saying that the attack under discussion targeted Penn Station, a major subway and rail hub in Manhattan.

'Madrid-like' attack

It said the plot involved a "Madrid-like attack", a reference to the bombing of Spanish trains in March 2004 that killed 191 people.

Extra police could be seen at Penn Station, with six squad cars parked together outside, as well as a command truck at a separate location.

Inside the station's hall for north-eastern Amtrak trains, five armed officers patrolled in helmets and flack-jackets, and with sniffer dogs.

"I see a lot of law enforcement, more than usual," said Wall Street worker Vishal Rawal, 25, who commutes daily between Manhattan and New Jersey.

"Of course I am concerned. Even if I am too busy with work, it is always on your back," he added.

Thursday is the US's Thanksgiving holiday, the unofficial beginning of the holiday season that ends with New Year's Day.