Plotters are said to have talked of flooding New York's financial district
US authorities say they have disrupted the early stages of a plot to blow up road tunnels around New York city.
The alleged plot was discovered during routine monitoring of internet chatrooms used by extremist groups.
Reports say one man has been arrested in Lebanon over the plot, but the FBI said it had no indication of imminent threats to New York's transport system.
Plotters are thought to have discussed targets including the Holland Tunnel which links Manhattan and New Jersey.
FBI agents said this was a plot to drive vehicles laden with explosives into several tunnels around Manhattan and then blow them up, the BBC's Nick Miles, in Washington, says.
The FBI says that information gleaned from the internet suggests the former al-Qaeda leader in Iraq, Abu Musab al-Zarqawi, had agreed to give his financial support.
But there is no evidence that any money was sent or explosives bought, our correspondent adds.
Reports quoting Lebanese security sources said a suspect in the plot - named as Amir Andalousi - had been arrested a month ago.
Senator Charles Schumer of New York said this was one instance "where intelligence was on top of its game and discovered the plot when it was just in the talking phase".
A number of plots targeting subways, tunnels and other New York City landmarks have come to light since the 2001 attacks on the World Trade Center.
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God Bless
Michelle!
I Am Inclined After Followen 911 To date--Most Of It Is Propaganda Bandanna...
Your Friend TRASK
B&R
Praise God for those who were alert to real and present danger...
Makes one wonder, if they missed any...in the past?
Good post, Peter. BE SAFE OUT THERE! Love & Prayers, Rhonda