The United States has thanked Pakistan for providing the information, which formed the basis  of the "extraordinary" terror alert issued by its Department for Homeland Security.

"With good allies in places like Pakistan, we are getting information that is more detailed and more specific than we had before about terrorists' plans and that allows us to better defend ourselves," US President George W Bush's National Security Adviser Condoleezza Rice said on Tuesday.

The information stemmed from documents discovered by Pakistan and US forces when they arrested key Al Qaeda operatives in Pakistan's Gujrat city last week.

Ahmed Khalfan Ghailani, a Tanzanian under indictment in New York for the 1998 embassy blasts that killed 224 people, and another unidentified operative nabbed following a 12-hour shootout after a CIA tip-off, had apparently carried with them detailed information about potential targets in Manhattan, New York and Washington.

Denying that the timing of the latest alert had anything to do with the US presidential election, Rice told NBC-TV that the warnings about possible terrorist attacks on financial centres in New York, New Jerey and Washington were on the basis of "specific information" that became available over the last several days.     

She emphasised that it was entirely possible that there could be additional targets in the terrorists' list.