The US commander in Afghanistan, General John Allen, is under investigation for "inappropriate"
emails to a woman linked to the sex scandal involving former CIA director David Petraeus, a defence official has said.
The revelation on Tuesday represented yet another stunning turn in a widening scandal that has jolted Washington only days after the re-election of President Barack Obama, with legislators vowing to get to the bottom of the case.
The Pentagon official told reporters the FBI had uncovered a trove of 30,000 pages of correspondence, mostly emails, between Allen and Jill Kelley, a key figure in the scandal that brought down the CIA chief.
Petraeus, a former four-star general who had previously led the US wars in Iraq and Afghanistan, resigned abruptly last week over an extramarital affair with his biographer Paula Broadwell.
Kelley, of Tampa, Florida, had alerted the FBI to receiving threatening emails earlier this year that were eventually traced to Broadwell. The FBI then found emails between Broadwell and Petraeus that revealed their affair.
The senior US defence official, speaking on condition of anonymity, told reporters travelling with Defence Secretary Leon Panetta there was a "distinct possibility" the Allen emails were connected to the Petraeus investigation.
"The allegations involve inappropriate communications" between Allen and Kelley, the official said.
The senior official, who discussed the matter only on condition of anonymity because it is under investigation, said Leon Panetta, the US defence secretary, believed it was prudent to launch a Pentagon investigation, although the official would not explain the nature of Allen's problematic communications.
|Jill Kelley is identified as the woman who allegedly received harassing emails from Paula Broadwell [AFP]
The official said the tens of thousands of pages of emails and other documents from Allen's communications with Kelley between 2010 and 2012 are under review.
He would not say whether they involved sexual matters or whether they are thought to include unauthorised disclosures of classified information. He said he did not know whether Petraeus is mentioned in the emails.
"General Allen disputes that he has engaged in any wrongdoing in this matter," the official said. He said Allen currently is in Washington.
Panetta has told reporters that while the matter is being investigated by the Defence Department Inspector General, Allen will remain in his post as commander of the International Security Assistance Force, based in Kabul. He praised Allen as having been instrumental in making progress in the war.
The FBI's decision to refer the Allen matter to the Pentagon rather than keep it itself, combined with Panetta's decision to allow Allen to continue as Afghanistan commander without a suspension, suggested strongly that officials viewed whatever happened as a possible infraction of military rules rather than a violation of federal criminal law.
Allen was Deputy Commander of Central Command, based in Tampa, prior to taking over in Afghanistan. He also is a veteran of the Iraq war.
In the meantime, Panetta said, Allen's nomination to be the next commander of US European Command and the commander of NATO forces in Europe has been put on hold "until the relevant facts are determined".
He had been expected to take that new post in early 2013, if confirmed by the US Senate, as had been widely expected.
Panetta said President Barack Obama was consulted and agreed that Allen's nomination should be put on hold.
Allen was to testify at his confirmation hearing before the Senate Armed Services Committee on Thursday. Panetta said he had asked committee leaders to delay that hearing.
Panetta also said he wants the Senate Armed Services Committee to act promptly on Obama's nomination of General Joseph Dunford to succeed Allen as commander in Afghanistan.
That nomination was made several weeks ago. Dunford's hearing is also scheduled for Thursday.
On Monday, the FBI searched the home of Broadwell in Charlotte, North Carolina, CBS television affiliate WFMY reported.
A reporter for WCNC tweeted that FBI agents were in Broadwell's home for at least two hours, starting at 8:40pm (01:40 GMT Tuesday).
Broadwell, who wrote a biography about the retired four-star general, has not been seen at her home since Petraeus resigned, citing the affair.
Retired colonel Steve Boylan, a friend and former Petraeus spokesman, said the affair between Petraeus and his biographer began about two months after he assumed his post at the CIA in September 2011, and thus after he retired from the US Army.
It ended about four months ago.
The affair unravelled when a Florida woman reportedly went to the FBI in the early summer after she began receiving threatening emails that were traced back to Broadwell.
The messages accused Kelley of flirting with the general, according to widely-reported leaks from US officials.
There is no suggestion that Kelley, a married woman from Tampa, Florida, had an affair with Petraeus.
In a statement, she and her husband acknowledged their friendship with Petraeus and asked for privacy.
The agents eventually discovered sexually explicit emails between Petraeus and Broadwell confirming the affair.
The pair was interviewed separately by investigators in late October and early November but, despite reports Broadwell was found to be in possession of some classified material, no criminal charges were brought.
Meanwhile, the FBI investigation itself has come under scrutiny.
According to the Wall Street Journal, supervisors pulled the whistleblower FBI agent off the case after he became "obsessed" with the matter and was caught sending Kelley shirtless photos of himself.