The book database at the centre of the claims, called Library Genesis, contained novels from a host of well-known Australian writers including Liane Moriarty, Trent Dalton, Tim Winton, Sally Hepworth and Charlotte Wood.
But AI technology experts say the issue may not be adequately addressed unless the US takes action, as Australian laws have proven difficult to prosecute across borders.
The claims against Meta were revealed in court documents as part of a copyright infringement lawsuit filed by authors including Sarah Silverman, Laura Lippman and David Henry Hwang.
The plaintiffs claim Meta abruptly ended attempts to licence published novels in order to claim fair use of the copyright material, and the issue was escalated "to Mark Zuckerberg and other Meta executives for approval".
A spokesperson for Meta declined to comment on the claims.
Australian author Kate Horan, whose novel The Inheritance appears in the database, said the idea her debut novel may have been used without her consent made her feel violated.
"My book came out on New Year's Day so it's been out for less than three months and it's already been stolen," she said.
"It's a weird mix of emotions to have something that you've worked on and that is a product of life experiences ... just stolen."
Tech companies that use copyrighted material without permission should be forced to compensate creators "at the very least", Ms Horan said, but she also called on the industry to take a stronger stance against theft.
"I would like to see publishers all working together against this," she said.
"We're going to have machines writing books and we're all going to be poorer as a result of that."
The news comes more than a year after claims another database of pirated novels, known as Books3, was used to train large language models from Meta, Bloomberg and EleutherAI.
These ongoing reports should reinforce the need for governments to take action to protect copyright holders, Media Entertainment and Arts Alliance chief executive Adam Portelli said, and to force companies to pay for the creative work they use.
"Mark Zuckerberg, one of the richest people in the world, has previously demonstrated his contempt for creative workers by saying they 'overestimate' the value of their work for training AI," Mr Portelli said.
"If they won't voluntarily compensate creative workers for using their output, governments need to step in to make them do so."
Australian laws or regulations may not be enough to protect local authors, University of the Sunshine Coast computer science lecturer Erica Mealy said, and laws regulating AI may need to come from the US government with international backing.
"We've seen where the eSafety Commissioner had trouble trying to enforce Australian law on American organisations," Dr Mealy said.
"But these are language-crafting tools and anything they've consumed they can reproduce so (AI use) really should be opt-in and there really should be some controls around copyright."
The federal government is considering mandatory guardrails to regulate the technology, including a potential AI act, and released voluntary AI guidelines in September.
