WASHINGTON -- The FBI publicly warned more than 1,200 banks in the Northeast on Friday of possible terrorist attacks, and government officials said the unconfirmed information that led to the dramatic alert came in part from a high-ranking al-Qaida leader in U.S. custody.

Authorities cautioned that they had no information about a specific plot or threats to any financial institution, but a U.S. law enforcement source said authorities feared a suicide attack. Another senior official said the threat was not specified.

The warning of what the FBI described as possible "physical attacks" was based in part on information from Abu Zubaydah, the highest-ranking al-Qaida terrorist leader in U.S. custody, two officials said, but it was unclear if he was telling the truth. Officials suggested he could be lying in an effort to create a panic.

Abu Zubaydah is alleged to have been one of Osama bin Laden's top planners of terrorist operations, with knowledge of al-Qaida plots and operational cells. He was captured March 28 by Pakistani and U.S. authorities in Pakistan and is recovering from three gunshot wounds he received in the raid.

There were no reports of any bank closings in response to the alert Friday.

"We are not changing our national threat level," said Attorney General John Ashcroft. "We are not asking the banks to close, nor urging people to stay away from banks."

He asked citizens to report suspicious activity to the FBI. Ashcroft said the information "may or may not be reliable."

The government has issued industry-specific warnings since Sept. 11 about possible attacks against trucking companies, dams and water-supply systems, crop dusters and nuclear plants.

Threats of merit

"Our policy is to share information with appropriate authorities and the American public when we have threat information that merits their attention," Ashcroft said. "We believe that this information sharing disrupts and prevents terrorist activity."

FBI Director Robert Mueller said, "Every threat has a different value in terms of credibility."

At a news conference in San Jose, Calif., Mueller added, "Down the road if we get more substantiation or corroboration or additional evidence of the credibility of the information, we would modify this warning."

White House spokesman Ari Fleischer said, "These things are always judgment calls about providing the country with information ... even if it's not a lot of information."

The FBI warning went to more than 1,200 banks and savings institutions and to law enforcement in Virginia, Maryland, Delaware, Pennsylvania, New York, New Jersey, Connecticut, Massachusetts, Rhode Island, Maine, Vermont, New Hampshire and the District of Columbia.