WASHINGTON — The FBI issued thousands of subpoenas to banks, phone companies and Internet providers last year, aggressively using a power enhanced under the Patriot Act to monitor the activities of U.S. citizens, Justice Department data released late Friday showed.
The report given to members of Congress was the first to detail the government's use of a controversial form of administrative subpoena that has drawn fire because it can be issued by investigators without court oversight.
The Justice Department report also disclosed that its use of electronic surveillance and search warrants in national security investigations jumped 15% in 2005.
The data show that U.S. authorities are in some cases escalating their use of anti-terrorism statutes.
Civil liberties groups said they found the new information worrisome. They said it raised concerns about whether investigators were being sensitive to the rights of citizens caught in terrorism-related probes.
The report includes the first look at the use of what are known as national security letters, which let the FBI obtain phone logs, Internet traffic records, and bank and credit information about individuals without a court order.
The Bush administration had fought the release of the information on grounds that it could imperil national security. But Congress ordered the release when it reauthorized portions of the Patriot Act this year.
According to the new report, the FBI issued 9,254 national security letters in 2005, covering 3,501 U.S. citizens and legal foreign residents.
The Justice Department said the data did not include what probably were thousands of additional letters issued to obtain more limited information about some individuals -- such as a home address -- or letters that were issued about targets who were in the U.S. illegally.
The number of such letters previously had been provided to members of Congress on a classified basis. Data from other years aren't available, although some experts said the number probably had increased substantially.
"Now we can see why the administration was so eager to hide the number," said Lisa Graves, a senior legislative counsel with the American Civil Liberties Union in Washington.
The original Patriot Act, enacted weeks after the attacks on the World Trade Center and the Pentagon, made it easier for the FBI to issue the letters, and for the first time permitted agents based outside Washington to issue the letters.
"These used to be fairly difficult to obtain, and now the authorities have been delegated very widely," said Michael Woods, former head of the FBI national-security law unit. "I think [the report] primarily shows that they are a lot easier to get."
The Justice Department report also included an annual update on the number of warrants that the department had obtained through the Foreign Intelligence Surveillance Court, a secret federal court for intelligence and terrorism investigations.
Applications for electronic surveillance and physical search warrants -- which almost always are approved by the court -- rose to 2,074 in 2005, compared with 1,758 in 2004. Last year's total was more than double the number sought in 2000.
That court is the tribunal that the Bush administration has been bypassing in a warrantless domestic surveillance program since shortly after Sept. 11.
James Dempsey, policy director of the nonprofit Center for Democracy and Technology in Washington, said the increased use of the secret court belied the government's contention that it needed to go outside the court to get the information it needed.
Dempsey said he was surprised the number of warrants issued by that court had continued to grow substantially "when the war on terrorism has reached a sort of steady state."