Amazon CEO Jeff Bezos on Thursday accused the publisher of the National Enquirer of "blackmail" after it threatened to publish intimate photographs sent by the billionaire to his mistress if he did not cease his investigation into how the newspaper got the pictures.

It comes after the tabloid, having accessed private text messages, last month reported Bezos had an extramarital affair with former news anchor and entertainment reporter Lauren Sanchez -- a leak that led to his divorce.

In a post on blogging platform Medium Thursday, Bezos said Enquirer publisher American Media Inc (AMI), led by David Pecker, approached him with a threat to publish the photos if he did not halt an investigation into the motives behind the leak.

He added the publication demanded he and security consultant Gavin de Becker, who is leading the probe, publically state they had "no knowledge or basis for suggesting that AMI's coverage was politically motivated or influenced by political forces."

De Becker mentioned in a recent Daily Beast interview that "strong leads point to political motives" -- and that he was interested in Lauren Sanchez's brother Michael, a vocal supporter of US President Donald Trump with links to his inner circle, as a possible perpetrator.

And in his Medium post, Bezos, who also owns The Washington Post, pointed to AMI and David Pecker's previous cooperation with Trump -- including payments made to suppress negative stories, currently under investigation by federal prosecutors.

Bezos, his newspaper and Amazon are all regular targets of Trump's signature Twitter tirades.

Bezos also raised the publisher's links to Saudi Arabia -- whose Crown Prince Mohammed bin Salman is accused of directing the murder of Post columnist Jamal Khashoggi.

"Rather than capitulate to extortion and blackmail, I've decided to publish exactly what they sent me, despite the personal cost and embarrassment they threaten," Bezos wrote in the post, which was entitled "No thank you, Mr. Pecker" and included copies of emails from AMI.

"Of course I don't want personal photos published, but I also won't participate in their well-known practice of blackmail, political favours, political attacks, and corruption. I prefer to stand up, roll this log over, and see what crawls out," he added.