Gavin de Becker, who hired to investigate how private messages were leaked to a tabloid, The Daily Beast was hacked to the murder of Jamal Khashoggi, a Saudi reporter who wrote for The Washington Post. Bezos owns The Post.
"Our investigators and several experts concluded with high confidence that the Saudis had access to Bezos' phone, and gained private information," de Becker wrote. He said he had provided US authorities with his findings.
The Saudi embassy in Washington didn't immediately respond to a request for comment.
The allegations come roughly two months after Bezos accused American Media Inc., which owns The National Enquirer, or attempted extortion. In a lengthy medium post, Bezos said AMI had threatened to publishof him and Lauren Sanchez, an actress, unless he said the publisher wasn't "politically motivated or influenced by political forces."
MacKenzie Bezos, his wife of 25 years,. His announcement came hours before The National Enquirer published a series of flirty texts between Bezos and Sanchez.
In his post, the Becker said it was unclear how much, if anything, knew about the alleged Saudi hack .
In a statement, an American media spokesperson called the Becker's claims "false and unsubstantiated," adding that Michael Sanchez, Lauren's brother, was the company's "single source" of information on the relationship. "There was no involvement with any other party whatsoever."
CNET could not reach Michael Sanchez for comment.
Previously said it wouldthe claims post
Originally published March 31, 9:59 am PT
Updates, 10:30 am.m. PT : Adds AMI comment.