He said while the brother of Bezos’s lover was paid by the National Enquirer scandal sheet for the release of the information, his role may have been a red herring, and the plot went far beyond one man trying to cash in.

“It’s clear that MBS considers The Washington Post to be a major enemy,” de Becker wrote, referring to the oil-rich kingdom’s powerful Crown Prince Mohammed bin Salman, whom the US Senate, after a closed-door briefing by the CIA, named as “responsible” for the murder.

But de Becker did not specify which part of the Saudi government he was blaming for the hack, and gave few details about the investigation that led him to the conclusion the kingdom was responsible.

The results, he wrote, “have been turned over to federal officials”.

Bezos hired Gavin de Becker & Associates to find out how his intimate text messages and photos made their way into the hands of the Enquirer, which reported on the Amazon chief’s extramarital affair with celebrity Lauren Sanchez, leading to his divorce.

The Amazon chief refused and instead, published copies of the emails from AMI, which insisted it acted lawfully in the reporting of the Bezos story.

In the Daily Beast article, de Becker said AMI privately demanded that he deny finding any evidence of “electronic eavesdropping or hacking in their newsgathering process”.

Regarding the alleged phone hacking, de Becker said “it is unclear to what degree, if any, AMI was aware of the details”.

In February, the kingdom’s minister of state for foreign affairs said Saudi Arabia had “absolutely nothing to do” with the National Enquirer’s reporting on the affair.

Saudi Arabia insists the crown prince was not involved in the killing of Khashoggi.

Riyadh initially said it had no knowledge of his fate, but later blamed the murder on rogue agents.

Additional reporting by Reuters