WASHINGTON / ABBOTTABAD - US officials sought to keep a lid on growing skepticism over Washington's version of events around Osama bin Laden's death, insisting the al-Qaida leader was killed during a firefight in the compound in Pakistan where he was hiding.

The White House has cited the "fog of war" as a reason for initial misinformation on whether bin Laden - who was shot in the head - was armed when US Navy SEALs raided his compound in the Pakistani town of Abbottabad early on Monday.

Citing US officials, NBC reported on Wednesday that four of the five people killed in the operation, including bin Laden, were unarmed and never fired a shot - an account that differs from the administration's original assertions the commandos engaged in a prolonged firefight.