Elon Musk has called for the "break up" of tech giant Amazon, following a dispute about a coronavirus e-book.
The entrepreneur came to the defence of an author after Amazon's Kindle publishing division rejected his book about the coronavirus pandemic.
Mr Musk tagged Amazon chief executive Jeff Bezos in a tweet, saying the decision was "insane", adding: "Time to break up Amazon."
Amazon said the book had been removed in error and would be reinstated.
The author of the book, Alex Berenson, caught Mr Musk's attention by tweeting a screenshot from Amazon, which told him that his book about the pandemic did not meet its guidelines.
"They censored it!" wrote Mr Berenson. "It is based entirely on published government data and scientific papers. It doesn't say coronavirus isn't real or doesn't kill people."
Mr Musk has been a critical of government policies during the coronavirus pandemic.
He has previously described shutdown orders as "fascist" and threatened to move Tesla's headquarters out of California when a production facility was not allowed to reopen.
Mr Musk and Mr Bezos are rivals in a race to make space travel more affordable.
Mr Musk founded SpaceX in 2002, two years after Mr Bezos started his rocket firm Blue Origin.
Last year, Mr Bezos criticised Mr Musk's hope of creating a Mars colony.
According to Business Insider, he said: "My friends who want to move to Mars? I say do me a favour: Go live on the top of Mount Everest for a year first and see if you like it because it's a garden paradise compared to Mars."