Security has been tightened at five key financial centres in the United States after what is described as a 'credible' threat from al-Qaeda.
Institutions mentioned as likely targets for attack included the New York Stock Exchange and the World Bank.
The authorities in Pakistan said information on possible planned attacks in the US came from a computer seized after the arrest of a key al-Qaeda suspect last week.
Proposals were said to be found in emails on the computer of Ahmed Khalfan Ghailani who was captured after a gun battle.
Meanwhile, employees at US financial institutions were urged to report for work despite the threats.
The security alert was raised to high - the second-highest level - in parts of Washington and New York.
The US Department of Homeland Security cited car and truck bombs as the most likely means of attack.
New intelligence post announced
Separately, the US President George W Bush announced the creation of a National Intelligence Director as part of an election-year overhaul meant to thwart future terrorist attacks.
Setting up the post was one of the proposals of the commission that investigated the 11 September attacks in 2001.
Mr Bush also announced the establishment of a national counter-terrorism centre, to serve as a data bank on terrorist activity.
The president was giving a public address at the White House to outline a reform of US security services.
