April 29 (Reuters) - Google has been hit with a new copyright lawsuit in California federal court by a group of visual artists who claimed the Alphabet unit used their work without permission to train Imagen, its artificial-intelligence powered image generator.

Photographer Jingna Zhang and cartoonists Sarah Andersen, Hope Larson and Jessica Fink said in the proposed class action filed Friday that Google is liable for misusing "billions" of copyrighted images, including theirs, to teach Imagen how to respond to human text prompts.

The case is one of many potential landmark lawsuits brought by copyright owners against tech companies including Microsoft, OpenAI and Meta over the data used to train their generative AI systems.

"Our AI models are trained primarily on publicly available information on the internet," Google spokesperson Jose Castaneda said on Monday. "American law has long supported using public information in new and beneficial ways, and we will refute these claims in court."

The artists' attorneys Joseph Saveri and Matthew Butterick said in a statement that the case was "another instance of a multi-trillion-dollar tech company choosing to train a commercial AI product on the copyrighted works of others without consent, credit, or compensation."

Zhang and Andersen are also involved in a similar ongoing lawsuit against Stability AI, Midjourney and others over the companies' alleged misuse of their work to train AI image generators. The lawsuit filed on Friday said that Google used one of the same datasets to train Imagen that Stability and Midjourney used to train their systems.

The artists asked the court for an unspecified amount of monetary damages and for an order forcing Google to destroy its copies of their work.

The case is Zhang v. Google LLC, U.S. District Court for the Northern District of California, No. 5:24-cv-02531.

For the artists: Joseph Saveri of Joseph Saveri Law Firm; Laura Matson of Lockridge Grindal Nauen; and Matthew Butterick