A United States Navy SEAL, who helped kill Osama bin Laden in Pakistan in 2011, allegedly kept an unauthorised photo of the corpse of the world's most wanted terrorist, a US news site reported.

Matthew Bissonnette turned over a hard drive that contained the photo to US investigators in exchange for an agreement that he would not be prosecuted for unlawfully possessing classified material, The Intercept reported.

The Obama administration has never released images of bin Laden's body, fearing that the photos would trigger a backlash. It has maintained that the al-Qaeda leader was buried at sea shortly after the raid.

Bissonnette, who reportedly shot bin Laden during the raid on the al-Qaeda leader's compound in the garrison city of Abbottabad in Pakistan, had been under investigation for allegedly making public classified information in his book about the 2011 incident, No Easy Day.

Bissonnette's lawyer, Robert Luskin, declined to comment to CNN on the contents of The Intercept article, the specifics of the information in question and whether there has been any ongoing contact between the Pentagon and Bissonnette's legal representation.

He did, however, said that previously a 'government investigation into alleged mishandling or improper disclosure of classified information by Matthew Bissonnette was closed in August 2015 with a declination'.