SAN FRANCISCO: Microsoft-backed OpenAI has been sued by another group of writers, claiming that the Sam Altman-run company illegally used their works to train its chatbot called ChatGPT.

Authors Michael Chabon, David Henry Hwang, Rachel Louise Snyder and Ayelet Waldman alleged in the lawsuit that OpenAI benefits and profits from the "unauthorised and illegal use" of their copyrighted content.

The lawsuit is seeking class-action status.

"OpenAI incorporated plaintiffs' and class members' copyrighted works in datasets used to train its GPT models powering its ChatGPT product," read the lawsuit.

"Indeed, when ChatGPT is prompted, it generates not only summaries, but in-depth analyses of the themes present in plaintiffs' copyrighted works, which is only possible if the underlying GPT model was trained using plaintiffs' works," it added.

The lawsuit alleged that "OpenAI's acts of copyright infringement have been intentional, willful, and in callous disregard of Plaintiffs' and Class members' rights.

"OpenAI knew at all relevant times that the datasets it used to train its GPT models contained copyrighted materials, and that its acts were in violation of the terms of use of the materials," it further claimed.

In July, comedian and author Sarah Silverman, along with authors Christopher Golden and Richard Kadrey, sued OpenAI and Mark Zuckerberg-owned Meta over dual claims of copyright infringement.

The lawsuits alleged that OpenAI's ChatGPT and Meta's LLaMA (a set of large language models) were trained on illegally-acquired datasets containing their works.

The US Federal Trade Commission (FTC) was also probing the ChatGPT developer over user data collection and the publication of false information.