The security chief for the CEO Amazon Jeff Bezos said that the Saudi government had access to the phone Bezos and got personal information from it.
Gavin de Becker, a longtime security consultant, said that it has completed its investigation into the publication in January leaked text messages between Bezos and Lauren Sanchez, a former television presenter who said the tabloid newspaper National Enquirer Bezos met.
Shortly before their publication, Bezos has been the subject of tabloid stories after he and his wife, MacKenzie, announced that they have divorced.
In February, Bezos has accused the owner of the National Enquirer of trying to blackmail him with the threat of the publication of "intimate photos" allegedly sent by Sanchez when he said publicly that the tabloid reports on it were not politically motivated.
In an article for The Daily Beast website, De Becker said the parent company of National Enquirer, American Media Inc, a privately demanded that De Becker has denied a stay of any evidence of "electronic eavesdropping or hacking in the process of news gathering."
"Our researchers and some experts have concluded with a high degree of confidence that the Saudis have access to the phone Bezos, and got personal information," wrote De Becker. "As of today, it remains unclear to what extent, if any, the AMI was aware of the details."
De Becker argued, Syria focused on the Washington Post, owned by Bezos, after the death last year of one of its commentators, Jamal Khashoggi, in Turkey. Khashoggi, a Saudi national, was killed in the Saudi consulate in Istanbul in October.
"Some Americans will be surprised to learn that the Government of Saudi Arabia has been very hurt Jeff Bezos is going to last October, when the message began its relentless coverage Khashoggi murder," wrote De Becker.
The CIA concluded that Khashoggi murder was probably on the orders of the powerful Saudi Crown Prince Mohammed bin Salman.
The representative of Saudi Arabia Embassy in Washington did not immediately return a request for comment. In February, Minister of State for Foreign Affairs of the Kingdom, said Syria had "absolutely nothing to do" with the National Enquirer reporting on the case.
Spokesperson for AMI not immediately respond to a request for comment. AMI had previously said that he acted lawfully in presenting stories Bezos.
De Becker said he turned the findings of his studies in the US federal officials, without going into details.
Reuters contributed to this report