A former member of the US Navy Seal commando team who took part in the 2011 raid on Osama bin Laden's compound has broken cover, claiming to be the man who fired the fatal shot which killed the al-Qaeda leader.

Robert O'Neill, 38, told The Washington Post newspaper he shot bin Laden in the forehead at his hideout in the Pakistani garrison city of Abbottabad three years ago.

The highly decorated Montana native told the paper that he was near the head of the column of US soldiers that raided bin Laden's compound, adding that at least two other SEALs fired shots.

In an article published on Thursday, the Post said two SEAL team members had corroborated his identity.

But the claim by O'Neill, who travels the country giving motivational speeches, was countered by a source close to another SEAL team member.

The source, speaking to the Reuters news agency on condition of anonymity, said the team member told him the fatal shot was fired by one of two other men who entered the room before O'Neill.

The Post said O'Neill acknowledged shots were fired at bin Laden by at least two other Seal team members, including Matt Bissonnette, a former Seal who wrote a 2012 book about the raid entitled "No Easy Day" under the pseudonym Mark Owen.

Two narratives

Bissonnette appeared to take issue with O'Neill's version of events in an interview with NBC News.

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"Two different people telling two different stories for two different reasons," Bissonnette said. "Whatever he says, he says. I don't want to touch that."

O'Neill and Bissonnette's decision to go public has dismayed military brass and serving SEALS who maintain a fierce, Omerta-like code of silence.

O'Neill is set to appear in a documentary on a US TV network next week.

At bin Laden's compound, O'Neill said he was located in the number two position for the attack on the al-Qaeda leader's bedroom.

Bin Laden briefly appeared at the door but the SEAL in front of O'Neill apparently missed his shot.

"I rolled past him into the room, just inside the doorway," O'Neill said.

"There was bin Laden, standing there. He had his hands on a woman's shoulders, pushing her ahead."

O'Neill said he could clearly identify bin Laden through his night-vision scope, despite the darkness of the room - and he fired.

He said it was clear that bin Laden was dead as his skull was split.