An investigator from Amazon boss Jeff Bezos says Saudi Arabia hacked Mr. Bezos' phone and accessed his data.
Gavin de Becker was hired by Mr. Bezos to find out how his private messages had penetrated the tabloid of the National Enquirer.
Mr de Becker linked the hack with Washington Post's coverage of the murder of Saudi writer Jamal Khashoggi in the Saudi consulate in Istanbul.
Saudi Arabia has not commented on the allegation yet.
Besos owns the Washington Post.
Mr. de Becker claimed to have passed his findings to US federal officials.
"Our investigators and several experts were convinced that the Saudis have access to the Bezos phone and receive private information," he wrote The Daily Beast website.
Mr. de Becker's findings came about after Bezos accused the American Enemy's National Enquirer of extortion in February of American Media Inc. (AMI). He threatened to publish his intimate photos, unless the tabloid coverage was not politically motivated.
Mr. de Becker said that AMI has also requested that his investigation conclude that AMI has not relied on "any form of electronic interception or hacking in its message-gathering process".
The Saudi government had targeted the Washington Post, for which Mr. Khashoggi had written.
"Some Americans will be surprised to learn that the Saudi government has been very focused on harming Jeff Bezos since last October, when the Post began tirelessly reporting Khashoggi's murder," said De Becker.
"It's clear Washington Post sees the Washington Post as a big enemy," he added, referring to Saudi Crown Prince Mohammed bin Salman.
US officials said that the killing of Mr. Khashoggi would have required the approval of Prince Mohammed, but Saudi Arabia has denied his involvement.
The Saudi Embassy in Washington has not responded to a request for comment on Mr. Salman de Becker's claim, Reuters reported.
In February, the Saudi Foreign Minister said Saudi Arabia had "absolutely nothing to do with the National Enquirer's coverage of Mr. Bezos's relationship."
AMI has not yet commented on the allegations made by Mr de Becker. The company previously stated that it had acted legitimately in reporting on the personal life of Bezos.