The artificial intelligence company Anthropic has been hit with a class-action lawsuit in California federal court by three authors who say it misused their books and hundreds of thousands of others to train its AI-powered chatbot Claude, which generates texts in response to users’ prompts.

The complaint, filed on Monday by writers and journalists Andrea Bartz, Charles Graeber and Kirk Wallace Johnson, said that Anthropic used pirated versions of their works and others to teach Claude to respond to human prompts.

“Anthropic styles itself as a public benefit company, designed to improve humanity. For holders of copyrighted works, however, Anthropic already has wrought mass destruction,” the complaint reads. “It is no exaggeration to say that Anthropic’s model seeks to profit from strip-mining the human expression and ingenuity behind each one of those works.”

The lawsuit joins several other high-stakes complaints filed by copyright holders including visual artists, news outlets and record labels over the material used by tech companies to train their generative artificial intelligence systems.

Separate groups of authors have sued OpenAI and Meta Platforms over the companies’ alleged misuse of their work to train the large-language models underlying their chatbots.

The case filed on Monday is the second against Anthropic following a lawsuit brought by music publishers last year over its alleged misuse of copyrighted song lyrics to train Claude. Anthropic did not immediately respond to a request for comment on Tuesday. An attorney for the authors declined to comment. Amazon has invested $4bn in Anthropic, which is itself an offshoot of OpenAI, creator of ChatGPT.

The authors said in their complaint that Anthropic had “built a multibillion-dollar business by stealing hundreds of thousands of copyrighted books”. Anthropic has drawn financial backing from sources including Amazon, Google and the former cryptocurrency billionaire Sam Bankman-Fried.

According to the complaint, the authors’ works were included in a dataset of pirated books that Anthropic used to train Claude. The lawsuit requested an unspecified amount of monetary damages and an order permanently blocking Anthropic from misusing the authors’ work.