The government disclosed Thursday it requested and won approval for a record 1,228 warrants last year for secret wiretaps and searches of suspected terrorists and spies, a reflection of aggressive efforts to prevent terror attacks in the United States.

U.S. Attorney General John Ashcroft (searchdisclosed the figures in a mandatory, two-paragraph report to the administrative office of the U.S. courts. Last year's total was significantly higher than the 934 warrants approved in 2001 and the 1,003 approved in 2000.

The FBI often uses these specialized warrants -- issued under the 1978 Foreign Intelligence Surveillance Act (search) -- to record the telephone calls and e-mails of citizens and immigrants believed to be agents of a foreign power.

Experts said the increase in this special category of warrants offsets a significant drop in traditional wiretaps in criminal cases. The federal courts administrator disclosed earlier this week that judges had authorized all but one of the 1,359 wiretap applications submitted in 2002. That was a 9 percent decrease from the 1,491 applications logged the previous year.

"People had wondered why there was a decrease in criminal wiretaps, and we thought it was most likely due to the increased use of FISA court-ordered surveillance," said Beryl A. Howell, former general counsel for the Senate Judiciary Committee. "This is consistent and bears out that view."

Operating with permission from a secretive federal court that meets regularly at Justice Department headquarters, the FBI has broken into homes, offices, hotel rooms and automobiles, installed hidden cameras, rummaged through luggage and eavesdropped on telephone conversations.

Besides break-ins, agents also have pried into safe deposit boxes, watched from afar with video cameras and binoculars and intercepted e-mails. They have planted microphones, computer bugs and other high-tech tracking devices.

Details about some FBI techniques emerge from court records spread across dozens of cases. But only a fraction of these surveillances each year result in any kind of public disclosure, so little is known outside classified circles about how they work.

The Patriot Act (search), which became law in October 2001, broadened the 1978 surveillance law by allowing the FBI to request warrants in investigations that aren't mostly focused on foreign intelligence.