Hollywood giants Walt Disney and NBCUniversal have filed a copyright lawsuit against Midjourney, claiming the generative AI firm's image generator tool is a "bottomless pit of plagiarism".

The companies have accused Midjourney of pirating their libraries and copying well-known characters without permission to train its image service and generate high quality reproductions. Star Wars' Darth Vadar, Frozen's Elsa, and Despicable Me's Minions are among the examples provided.

The lawsuit, filed in federal district court in Los Angeles on Wednesday, marks the first high profile battle between Hollywood and an AI firm, following a number of smaller suits lodged by independent artists.

"By helping itself to plaintiffs' copyrighted works, and then distributing images (and soon videos) that blatantly incorporate and copy Disney's and Universal's famous characters -- without investing a penny in their creation -- Midjourney is the quintessential copyright free-rider and a bottomless pit of plagiarism," alleged the suit.

In a statement to Reuters, Disney executive vice president and chief legal officer, Horacio Gutierrez, said: "We are bullish on the promise of AI technology and optimistic about how it can be used responsibly as a tool to further human creativity, but piracy is piracy, and the fact that it's done by an AI company does not make it any less infringing."

NBCUniversal Executive Vice President and General Counsel Kim Harris told Reuters the company was suing to "protect the hard work of all the artists whose work entertains and inspires us and the significant investment we make in our content."