U.S. President Barack Obama said Wednesday he has no knowledge that any classified information or intelligence has been leaked as part of the recent scandals involving former CIA director David Petraeus and top U.S. military commander Gen. John Allen.

Speaking at the White House, Obama held his first news conference Wednesday since the scandal broke last week.

"I have no evidence at this point, from what I've seen, that classified information was disclosed that in any way would have had a negative impact on our national security," Obama said.

He added that the investigation is ongoing, and he didn't want to speak to the specifics of the case.

Petraeus resigned from his position as head of the CIA last week and admitted to having an extramarital affair with his biographer Paula Broadwell.

Their relationship was discovered during an FBI investigation into threatening emails received by a married Tampa woman named Jill Kelley, who was later found to be having a “flirtatious” correspondence with Allen, who is also married.

On Wednesday, the New York Times identified the FBI agent who spearheaded the initial investigation as Frederick Humphries, who played a key role in the “Millennium Bomber” case in 1999.

According to a report by the Seattle Times, Humphries reportedly went to high school in Ontario, but it’s unclear if he was born in Canada.

Obama was asked Wednesday whether he believed the FBI should have informed him sooner that Petraeus was under investigation. He declined to answer directly, saying he was reserving judgement on that front until he had more details about the investigation.

"One of the challenges here is we're not supposed to meddle in criminal investigations and that's been our practice," Obama said.

He went on to say that Petraeus has "provided this country with extraordinary service" as a military leader in Afghanistan and Iraq, and as the head of the CIA, and he hoped the scandal would eventually become a "single side note" on an otherwise respectable career. 

Benghazi probe

Earlier Wednesday, the question of whether Petraeus' sudden resignation would exempt him from answering lawmakers' questions was put to rest, when it emerged that the former CIA director has agreed to give evidence about the deadly attack on the U.S. Consulate in Benghazi, Libya.

Senate Intelligence Committee chair Dianne Feinstein said Wednesday that Petraeus has told her he will appear.

"He is very willing and interested in talking to the committee," she said, explaining that his testimony will be restricted to the events in Benghazi that killed four, including U.S. Ambassador Christopher Stevens. He will not speak to the extramarital affair that led to his resignation last Friday.

His appearance date has not been set.

According to Georgetown University professor George Christopher Swift, the focus on scandal distracts from Obama's other agenda.

"To the extent this scandal is a distraction, it's going to make things much more difficult for the White House to manage," Swift told CTV's Canada AM, speaking from Washington.

"There are about 15 working days between now and the end of the year before sequestration goes into effect," he added, referring to the looming fiscal cliff.

Unless Obama can implement his plan to avoid the consequences of expiring tax cuts and across-the-board spending cuts put off when lawmakers failed to reach a debt-reduction deal, the U.S. economy is expected to take a major hit. Analysts are predicting an instant dip into recession and a spike in unemployment.

"Those things have huge national security implications, not just for the United States, but also for our allies and neighbours," Swift said.

Continued confidence

Earlier in the day, U.S. Secretary of Defense Leon Panetta had warned against jumping to conclusions in the Petraeus affair and the subsequent investigation of another top U.S commander, Gen. John Allen.

In his first public comments on the matter, Panetta said he supports Allen, who is the top U.S. commander in Afghanistan.

"He certainly has my continued confidence to lead our forces and to continue the fight," Panetta told reporters in Perth, Australia, steering clear of speculation why Allen is being investigated for what officials have said may be "inappropriate" correspondence with Jill Kelley.

"No one should leap to any conclusions here."

Many are doing just that, however, considering that Kelley was the recipient of threatening emails from Paula Broadwell, the woman with whom Petraeus has admitted to having an extramarital affair after he resigned from his job as CIA director on Friday.

Both Kelley and Allen are married, raising the prospect of Allen facing charges of adultery under the U.S. Uniform Code of Military Justice, if they are found to have had an intimate relationship.

Allen has not commented publicly on the matter, but The Associated Press reports he told chairman of the Joint Chiefs of Staff Gen. Martin Dempsey he is innocent of misconduct, according to Dempsey's spokesperson Col. David Lapan.

One senior U.S. official, speaking on condition of anonymity, said the communications between Allen and Kelley were relatively innocent -- not sexually explicit or seductive -- and included pet names such as "sweetheart" and "dear."

When she was asked for comment, U.S. Secretary of State Hillary Clinton gave the questions of scandal a wide berth, focusing instead on the security implications.

"There has been a lot of conversation, as you might expect, but no concern whatsoever being expressed to us because the mission has been set forth and it's being carried out," Clinton said, telling reporters in Perth the matter has been broached with America's allies.

Panetta announced Tuesday, en route to Australia, that Allen was the subject of an internal investigation called after the FBI disclosed its own probe of the general. In his announcement Panetta said Allen would continue his command role in Afghanistan, but his nomination to be the next chief of U.S. European Command and top NATO general would be put on hold.