Obama at Ground Zero amid raid story doubts

The American leader will hope to begin to bury the memory of the terror chief by honouring those who died in the September 11 attacks on the World Trade Centre.

He will hold private talks with 9/11 families and first responders and lay a wreath at the 9/11 memorial.

But the visit comes as a senior US defence official revealed only one of the five people killed in the raid on bin Laden's compound was armed and fired a shot.

The official presented a very different account to the administration's original portrayal of a chaotic, intense and prolonged firefight.

He said the sole shooter in the al Qaeda leader's Pakistani compound was shot dead in the early minutes of the operation.

Details have become clearer now the Navy Seal commando assault team has been debriefed, the official said, speaking on condition of anonymity because he was not authorised to speak on the record.

He said the raid should be described as a precision, floor-by-floor operation to hunt and find the al Qaeda leader and his protectors.

As the Navy Seals moved into bin Laden's compound, they were fired on by bin Laden's courier, who was in the guesthouse, the official said.

The commandos returned fire, and the courier was killed, along with a woman with him. The official said she was hit in the crossfire.

The Americans were never fired on again as they encountered and killed a man on the first floor and then bin Laden's son on a staircase, before arriving at bin Laden's room.

Officials had said bin Laden was killed after he appeared to be reaching for a weapon.

US TV network NBC reports the majority of the operation was spent gathering up the computers, hard drives, mobile phones and other items that could offer valuable intelligence on al Qaeda and potential operations worldwide.

A White House spokesman had previously referred to "many other people who were armed in the compound", with others claiming bin Laden had taken part in the shoot-out.