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.

It comes after the tabloid last month reported Bezos was in a relationship with former news anchor and entertainment reporter Lauren Sanchez -- having accessed private text messages.

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 that 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 recent that "strong leads point to political motives." Bezos, who owns The Washington Post, is a consistent subject of criticism by US President Donald Trump.

"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.

"Be assured, no real journalists ever propose anything like what is happening here," he added.