Obama Backs Allen over Petraeus Sex Scandal

President Barack Obama gave his backing to the commander of U.S. forces in Afghanistan on Tuesday after the top general was dragged into the sex scandal that brought down CIA director David Petraeus.

General John Allen was placed under investigation after FBI agents probing email threats sent by Petraeus' mistress stumbled upon a vast trove of "flirtatious" messages Allen sent to another woman at the heart of the scandal.

According to a senior Pentagon official, Allen denies any sexual liaison with the woman, 37-year-old Tampa socialite Jill Kelley, but the "sheer volume" of correspondence could be found to amount to "conduct unbecoming an officer."

Due to face lawmakers this week for a hearing to confirm his promotion to the post of NATO's supreme commander in Europe, Allen will now return to Kabul and remain in charge in Afghanistan until the investigation is over.

"I can tell you that the president thinks very highly of General Allen and of his service to his country, as well as the job he has done in Afghanistan," White House spokesman Jay Carney told reporters.

"He has faith in General Allen," he added, referring reporters' questions on the inquiries into both Allen and Petraeus to the Pentagon, the FBI and the Justice Department.

Washington was already reeling from Petraeus' shock resignation when it learned that Allen -- who served with him in Iraq and at U.S. Central Command in Tampa, Florida -- had also been caught up in the scandal.

Petraeus resigned last week when it became clear that his affair with married 40-year-old military reservist Paula Broadwell, a military academic who wrote a fawning biography of the general, would become public.

FBI agents stumbled on the liaison after a complaint from Kelley -- a married Tampa woman and close friend of both Petraeus and Allen -- who told a federal agent that she had received threatening emails.

Investigators traced the mails to Broadwell's account and discovered that she had been in a relationship with Petraeus, despite both being married.

The threatening emails she had sent to Kelley -- who told investigators she did not know Broadwell -- suggest the biographer was jealous of the socialite's rapport with the generals at U.S. Central Command in Florida.

In one, according to the Wall Street Journal, Broadwell claimed she had seen Kelley touching "him" provocatively under the table. It is not clear who "him" was.

It emerged Tuesday that the agents had also discovered that Allen had sent a huge number of mails to Kelley, triggering an investigation into whether he had broken the law or any military regulations during the friendship.

In all, the FBI is investigating between 20,000 to 30,000 pages of Allen's correspondence, a Pentagon official told reporters traveling with US Defense Secretary Leon Panetta to Australia.

The Washington Post, citing a senior military official close to Allen, reported that the correspondence included 200 to 300 emails between Kelley and the general.

Petraeus and Broadwell were interviewed separately by investigators in late October and early November and both admitted to the affair.

Petraeus reportedly planned to remain in office and tough it out until last week, when the realization that the scandal was about to go public prompted him to offer Obama his shock resignation.

Petraeus had been due to testify to Congress this week on the September 11 assault in Benghazi, Libya that killed four Americans, including U.S. ambassador Chris Stevens and two former Navy SEALs working for the CIA.

The attack, which targeted the U.S. consulate and a secret CIA-run annex, raised questions about whether staff were adequately protected as they operated in the chaotic aftermath of last year's Arab Spring uprising.

Now U.S. legislators also want to know why the FBI and the Justice Department did not notify them or the White House sooner about the Petraeus investigation.

The inquiry comes at a sensitive time for Allen and the Pentagon, who are preparing their recommendations to the White House on the political hot button topic of the number of U.S. troops to keep in Afghanistan until 2014.

Petraeus took command of the CIA 14 months ago, retiring from the military after a glittering career that saw him lead the 101st Airborne, the U.S. war in Iraq, its CENTCOM regional command and international forces in Afghanistan.

The retired four-star general, who presided over the 2007 troop "surge" in Iraq, is widely credited with turning the tide of the U.S. war there, though similar efforts have been less successful in Afghanistan.

On Monday, FBI agents searched Broadwell's North Carolina home, removing bags, boxes and pictures, local media reported. The mother of two has not been seen at her home since Petraeus resigned over the affair.

The Federal Bureau of Investigation itself has also come under scrutiny.

On Tuesday, the Wall Street Journal reported that the FBI agent Kelley contacted about the threatening emails, a personal acquaintance of hers, brought the matter to the attention of Republican lawmakers.

The agent apparently believed the bureau was not moving aggressively enough with the investigation, suspecting that his superiors were keen to protect the Democratic president from the fallout.

FBI supervisors had earlier barred the agent from any involvement in the case after he became "obsessed" with the matter, the Journal said.

It quoted one official as saying the agent had sent shirtless photos to Kelley well before the email investigation had begun, and said he is currently under investigation by the internal affairs arm of the FBI.