WASHINGTON — The FBI secretly sought information last year on 3,501 U.S. citizens and legal residents from their banks and credit-card, telephone and Internet companies without a court's approval, the Justice Department said on April 28.

It was the first time the Bush administration had publicly disclosed how often it has used the administrative subpoena known as a National Security Letter, which allows the executive branch of government to obtain records about people in terrorism and espionage investigations without a judge's approval or a grand jury subpoena.

The disclosure was mandated as part of the renewal of the Patriot Act, the administration's sweeping anti-terror law.

The FBI delivered a total of 9,254 NSLs relating to 3,501 people in 2005, according to a report submitted late April 28 to Democratic and Republican leaders in the House and Senate. In some cases, the bureau demanded information about one person from several companies.

The numbers from previous years remain classified, officials said.

The department also reported it received a secret court's approval for 155 warrants to examine business records last year under a Patriot Act provision that includes library records. However, Attorney General Alberto Gonzales has said the department has never used the provision to ask for library records.

The number was a significant jump over past use of the warrant for business records. A year ago, Gonzales told Congress there had been 35 warrants approved between November 2003 and April 2005.

The spike is expected to be temporary, however, because the Patriot Act renewal that President Bush signed in March made it easier for authorities to obtain subscriber information on telephone numbers captured through certain wiretaps.

The Foreign Intelligence Surveillance Court, the same panel that signs off on applications for business-records warrants, also approved 2,072 special warrants last year for secret wiretaps and searches of suspected terrorists and spies. The record number is more than twice as many as were issued in 2000, the last full year before the terrorist attacks of Sept. 11, 2001.

The FBI security letters have been the subject of legal battles in two federal courts because, until changes were made in the Patriot Act, recipients were barred from telling anyone about them.

Ann Beeson, the associate legal counsel for the American Civil Liberties Union, said the report to Congress "confirms our fear all along that National Security Letters are being used to get the records of thousands of innocent Americans without court approval."

The number disclosed April 28 excludes requests for subscriber information, an exception written into the law. It was unclear how many FBI letters were not counted for that reason.

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