NEW YORK -- The FBI disrupted a plot by al Qaeda allies to detonate a bomb in a PATH commuter train tunnel from New Jersey to Manhattan, authorities said yesterday.

A 31-year-old man, described as the mastermind of the scheme, was jailed in Lebanon after allegedly confessing his role and admitting his allegiance to Osama bin Laden. Two other men were detained overseas and five more, also foreign born, have been identified as suspects, agents said.

Officials were reluctant to provide details of the plot, but cautioned that there was no imminent threat to residents or commuters. The alleged terror cell was discovered in 2005, and investigators said planners hoped to carry out an attack in October or November of this year.

None of the suspects had entered the United States, and agents found no evidence that they had amassed weapons.

Still, authorities said the investigation provided a stark reminder that the United States and particularly New York City remains an active terrorism target.

"This is a plot that would have involved martyrdom, explosives and certain of the (PATH) tubes that connect New Jersey to Lower Manhattan," said Mark Mershon, the assistant director in charge of the FBI's New York Division.

The Port Authority Trans-Hudson trains carry about 215,000 passengers each weekday between New Jersey and lower Manhattan. Two PATH lines end at the site of the former World Trade Center.

Assem Hammoud, the alleged mastermind, was jailed on terror-related charges by the Lebanese Internal Security Forces, officials said. There was no indication that he would face prosecution in the United States.

Investigators declined to identify the other suspects, or those who had been detained, because they said they had not been charged.

The probe, launched last year, spanned three continents. Led by the FBI, it also involved the New York Police Department, the Port Authority police and agencies in six foreign nations.

FBI and state homeland security officials in New Jersey said they had been aware of the investigation, but declined to elaborate.

News of the arrests coincided with the one-year anniversary of the London subway bombings that killed 52 people and injured hundreds more.

Mershon said the bureau had hoped to keep the plot secret but was forced to disclose it after details were reported in yesterday's editions of the New York Daily News.

Citing unnamed sources, the newspaper said the terror suspects hoped to detonate a bomb in the Holland Tunnel and unleash devastating floods in the city's financial district. Agents learned of the plot by monitoring Internet chat rooms, according to the newspaper.

Authorities disputed that the tunnel was the key target, but refused to say how they identified the suspects or their intentions.

Mershon criticized the public disclosure, saying the unauthorized leak led to "a number of uncomfortable questions and some upset" among foreign intelligence agencies. He said the paper's source was "clearly someone who doesn't understand the fragility of international relations."

NYPD Commissioner Raymond Kelly and Port Authority Police Superintendent Samuel Plumeri said they had increased the number of officers in Lower Manhattan and on the commuter trains in recent weeks. Kelly stressed that the plot "had not reached anything close to operational" but said it showed that the city was under constant threat.

"New York still remains in the cross hairs of the terrorists," he said.

The disclosure comes at the same time New York leaders have been decrying cuts in federal counterterrorism funding. Officials were cautious not to link the two.

"The amount of money that we get from Homeland Security does not directly impact the quality or the magnitude of our efforts to keep this city safe, nor will it," Mayor Michael Bloomberg said. "Whether we got the security moneys or not, this has nothing to do with this plot."

At a public appearance in Boston, Homeland Security Secretary Michael Chertoff said his department was made aware of the probe several months ago. He said the investigation reflects improved global cooperation and intelligence in counterterrorism efforts, and that the public should remain vigilant but calm.

"I wouldn't hesitate to tell my family to get on the subway here or all over the country to ride," Chertoff said. "We shouldn't give terrorists the idea they can scare us off our trains."


Staff writers Robert Cohen and Rick Hepp contributed to this report. © 2006 The Star Ledger