General John Allen, who is now under investigation by the FBI for allegedly exchanging thousands of “inappropriate” emails with military socialite Jill Kelley, simply called her “sweetheart”, a top official has claimed today.

In a dramatic new twist in the David Petraeus sex scandal, General John Allen reportedly exchanged 20,000 to 30,000 emails with Jill Kelley, the woman who sparked the probe into the CIA boss.

Jill Kelley, a housewife and unpaid social liaison for the military in Tampa, tipped off the FBI about threatening emails from David Petraeus’ mistress, Paula Broadwell, exposing the affair and leading to his resignation.

These latest revelations mean General John Allen, who is married with two adult daughters, is the second top military official to be dragged into the David Petraeus scandal.

John Allen, who is under FBI investigation for exchanging thousands of inappropriate emails with Jill Kelley, simply called her sweetheart

John Allen, 58, succeeded David Petraeus in Afghanistan and was due to take over as NATO’s top commander – but his appointment has been suspended while his relationship with Kelley is investigated.

A top official told the Washington Post that John Allen simply used the word “sweetheart” – which he said proves nothing as the general is from Virginia, where it is used as a platonic phrase.

“He’s never been alone with her,” the official said.

“Did he have an affair? No.”

The senior official added that Kathy Allen, the general’s wife, and Jill Kelley were “good friends”.