WASHINGTON (AFP) - The former United States Navy Seal who claims to be the soldier who fired the shots that killed Osama bin Laden is being investigated for possibly leaking classified information, the US military confirmed on Tuesday.

US Navy spokesman Ryan Perry said investigators were probing claims that Mr Rob O'Neill had broken the law by disclosing details about the daring 2011 raid that ended a 10-year manhunt for Osama.

"The Naval Criminal Investigative Service (NCIS) is in receipt of an allegation that Mr O'Neill may have revealed classified information to persons not authorized to receive such information," Mr Perry said in an email to AFP. "In response, NCIS has initiated an investigation to determine the merit of the allegations."

Mr O'Neill, 38, ignited a firestorm of controversy last month after coming forward to claim that he was the man who shot Osama through the forehead at his hideout in Abbottabad three years ago.

The highly decorated Montana native told The Washington Post that he was near the head of the column of US soldiers that raided Osama's compound, adding that at least two other Seals fired shots.

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

Another former Seal, Mr Matt Bissonnette, who published his account of the raid, No Easy Day in 2012, took issue with Mr O'Neill's version of events.

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

Mr O'Neill told the Post he had decided to come forward after meeting relatives of victims of the Sept 11, 2011 attacks on the World Trade Center in New York.

"The families told me it helped bring them some closure," Mr O'Neill told the Post.