Former CIA Director David Petraeus is preparing to field questions on Friday from US lawmakers about the attack on the US Consulate in Libya, his appearance on Capitol Hill coming one week after he resigned over an extramarital affair.

Petraeus is under investigation by the agency for possible wrongdoing, though that's not the subject of the closed-door hearings he is set to attend. The September attack in Benghazi, which killed the US ambassador and three other Americans, created a political firestorm, with Republicans claiming that the White House misled the public on what led to the violence.

Lawmakers spent hours on Thursday interviewing top intelligence and national security officials in trying to determine what the intelligence community knew before, during and after the Benghazi attack. They viewed security video from the consulate and surveillance footage by an unarmed CIA Predator drone that showed events in real time.