Amazon's share price fell in early trading today, after it emerged that a group of more than 1,000 authors were poised to take the standoff with publisher Hachette to the US Department of Justice.
Shares at the internet giant were down 0.7 per cent in mid-morning trading in New York.
Writers including Malcolm Gladwell, Donna Tartt and Stephen King are among those to have put their name to a letter that membership group Authors United plans to send to William J Baer, assistant US attorney general for antitrust.
The letter will call on the US authorities to "examine Amazon's business practices", according to the Financial Times.
Author and founder of the group Douglas Preston told the paper: "It's not an emotional or a populist appeal, it's simply citing points of law."
"[The DoJ] are expecting this letter and they have told me that they welcome any information we can provide."
Amazon, which today also revealed it was boosting its Silicon Valley team to test "smart home" devices - did not respond to a request for comment.
This is just the most recent chapter in a long-fought war between the two businesses over the terms of ebook pricing and marketing payments, which has led to a standoff in which Amazon has effectively blocked the purchase of Hachette titles.
Authors United estimates that these measures have affected more than 7,000 titles by 2,500 authors, in some cases reducing sales through Amazon by as much as 90 per cent.
Hachette is one of the world's biggest publishers, home to a vast number of key authors through its various imprints including Headline, Hodder & Stoughton and Little, Brown.
The publisher has widespread support from the writing community. Jack Reacher author Lee Child spoke out in defence of Hachette on Newsnight last month.
This is not the first time the DoJ and other authorities have been called on to settle antitrust matters in the book industry - and it is unlikely to be the last.
Previously five of the biggest publishing houses, including Hachette, HarperCollins, Penguin, Macmillan and Simon & Schuster, agreed to pay $166m in fines over accusations they conspired with Apple to raise ebook prices.