At a House Judiciary Committee hearing Tuesday, Valerie Caproni, the bureau's general counsel was apologetic and said steps were being taken to rectify problems found by Justice Department Inspector General Glenn Fine, The Washington Post reported.
Fine's report said the FBI may have violated the law or government policies as many as 3,000 times since 2003 by agents secretly collecting telephone, bank and credit card records using national security letters instead of subpoenas.
U.S. Rep. Dan Lungren, R-Calif., told Caproni the agency had betrayed trust.
"I just want to convey to you how upset many of us are who have defended this program and have believed it is necessary to the protection of our country," Lungren said.
Caproni did not challenge the criticism, The New York Times said.
"I think the public should be concerned. We're concerned. And we're going to fix it," she said.