The world's richest man, Amazon founder Jeff Bezos, has accused the owner of a US gossip magazine of trying to blackmail him over private pictures.
He said the National Enquirer's parent company, American Media Inc (AMI), wanted him to stop investigating how they had obtained his private messages.
Hours after Mr Bezos announced his divorce last month, the magazine published details, including private messages, of an extramarital affair.
AMI says the company "acted lawfully".
"American Media believes fervently that it acted lawfully in the reporting of the story of Mr Bezos. Further, at the time of the recent allegations made by Mr Bezos, it was in good faith negotiations to resolve all matters with him," the company said in a statement.
"Nonetheless, in light of the nature of the allegations published by Mr Bezos, the Board has convened and determined that it should promptly and thoroughly investigate the claims. Upon completion of that investigation, the Board will take whatever appropriate action is necessary."
The billionaire, who also owns the Washington Post newspaper, said AMI had wanted him to make a "false public statement" that the National Enquirer's coverage of him and his mistress was not politically motivated.
Jeff Bezos and his wife MacKenzie Bezos announced their separation last month
According to emails included by Mr Bezos in his blog, an AMI lawyer proposed on Wednesday that the photos would not be published in return for a public statement "affirming that [Bezos and his team] have no knowledge or basis" to suspect such a motive.
It comes after Mr Bezos' investigator suggested they had "strong leads" to suspect political reasons.
"Rather than capitulate to extortion and blackmail," wrote Mr Bezos, "I've decided to publish exactly what they sent me, despite the personal cost and embarrassment they threaten."
Early in the blog post, Mr Bezos mentions AMI's links to President Donald Trump.
Former TV host Lauren Sanchez is reported to be in a relationship with Mr Bezos
What has AMI said?
Reacting to the allegations on Friday, AMI said the company "believes fervently that it acted lawfully in the reporting of the story of Mr Bezos".
AMI said that they had been "in good faith negotiations to resolve all matters with him" when the allegations were made, and that the board "has convened and determined that it should promptly and thoroughly investigate the claims".
Why does Bezos mention Trump?
Mr Bezos said his ownership of the Washington Post was a "complexifier" for him because he had made enemies of "certain powerful people", including President Trump, who is a friend of AMI's boss, David Pecker.
AMI recently admitted in court that it had co-ordinated with the Trump presidential campaign to pay a Playboy model $150,000 (£115,000) in hush money to keep quiet about her alleged affair with Mr Trump.
Mr Bezos notes in his blog post how the publisher had confessed to the so-called "catch and kill" deal to bury Karen McDougal's politically embarrassing story.
AMI's agreement to co-operate with federal authorities means it will not face criminal charges over the payments, Manhattan prosecutors announced in December.
Mr Trump's former lawyer Michael Cohen - who facilitated the hush money at the direction, he says, of Mr Trump - has already admitted violating campaign finance laws.
Full story at https://www.bbc.com/news/world-us-canada-47166938