FBI Director Robert Mueller on Thursday staunchly defended a pair of controversial government surveillance programs, telling Congress that leaking information on them harms national security.

In his final appearance as FBI director before the House Judiciary Committee, Mueller said that “every time that we have a leak like this — and if you follow it up and you look at the intelligence afterwards — they are looking at the ways around it.”

“One of my problems is that we’re going to … lose our ability to get their communications. We are going to be exceptionally vulnerable,” he declared.

Last week’s revelations that the National Security Agency is collecting millions of U.S. phone records along with digital communications stored by nine major Internet companies have touched off a fiery national debate. The Obama administration, in its efforts to thwart terrorism, has overstepped proper bounds by using intrusive surveillance methods whose scope is stunning, several lawmakers suggested.

The admitted leaker of the NSA’s secrets, 29-year-old contractor Edward Snowden, is the subject of an ongoing criminal investigation, Mueller testified.

Responding to questions by committee chairman Rep. Bob Goodlatte, R-Va., Mueller said the Foreign Intelligence Surveillance Court has approved the surveillance programs and they have been conducted in compliance with U.S. law and with oversight from Congress.

Rep. John Conyers, the committee’s ranking Democrat, said “it’s my fear that we are on the verge of becoming a surveillance state.”

In defending the programs, Mueller called attention to the run-up to the Sept. 11, 2001 terrorist attacks, saying that if the controversial surveillance efforts had been in place back then, they might have uncovered the hijackers’ plot.

“If we had had this program, that opportunity would have been there,” said Mueller.

“I am not persuaded that that makes it OK to collect every call,” Conyers replied.

Mueller is nearing the end of his 12 years as head of the law enforcement agency that is conducting high-profile investigations of the Boston Marathon bombings, the attacks in Benghazi, Libya, that killed four Americans as well as leaks of classified government information. Mueller’s last day on the job is Sept. 4.

“These leaks illustrate the delicate balancing act between the need to protect national security information and investigate leaks, and the need to preserve the First Amendment to freedom of the press, said Goodlatte.

The Justice Department revealed last month that it had secretly gathered phone records of The Associated Press and emails of Fox News journalist James Rosen in an effort to crack down on leakers of classified information.

“The Obama administration takes credit for having investigated more national security leaks than any previous administration,” said Goodlatte. “While this may be true, I’m not certain whether it is due to a more aggressive investigative approach to national security leaks or the simple fact that there have been a shockingly high number of leaks in the last 4½ years.”

The FBI director also underwent questioning about the aftermath of the Boston Marathon bombings when impending court proceedings cut short the interrogation of accused bomber Dzhokhar Tsarnaev.

“In a very narrow sliver of cases where it is terrorism, where the threat is substantial, I would say that one could look at opportunities for giving those questioners additional time to extract information that may protect the public,” Mueller replied.

On Benghazi, Republicans accuse the administration of misleading the public about an act of terrorism in the heat of the presidential campaign by saying the Sept. 11, 2012, assaults on the U.S. diplomatic post grew out of spontaneous demonstrations over an anti-Muslim video. In the immediate aftermath, U.N. Ambassador Susan Rice described it as a “horrific incident where some mob was hijacked, ultimately, by a handful of extremists.” The White House says Rice reflected the best information available while facts were still being gathered.

Goodlatte said the committee planned to find out more about the status of what the congressman called the FBI’s “stalled investigation” in Libya.

GOP lawmakers also have questioned why the military couldn’t get aircraft or troops to Benghazi in time to thwart a second attack after the first incident that killed U.S. Ambassador Chris Stevens. Four Americans, including Stevens, died in the attacks that took place several hours apart.

(AP)