Thousands of artists including ABBA singer Bjorn Ulvaeus, Hollywood actress Julianne Moore and Nobel laureate Kazuo Ishiguro have signed a statement warning about the unlicensed use of artificial intelligence.

Some 11,500 stars of music, literature, screen and stage had put their names to the statement by Tuesday, as fears mount over tech companies using existing creative works to train up AI models without permission from their original creators.

"The unlicensed use of creative works for training generative AI is a major, unjust threat to the livelihoods of the people behind those works, and must not be permitted," says the brief statement.

In Hollywood, studios have been experimenting with AI in recent years, from bringing deceased movie stars back using realistic "digital replicas," to using computer-generated background figures to reduce the number of actors needed for battle scenes.

Similar fears have gripped other creative industries.

The statement was organized by British composer and former AI executive Ed Newton-Rex, the Guardian reported.

Newton-Rex told the newspaper that generative AI companies including his former employer Stability AI were using copyrighted contented to train their models without paying the original creators.

"When AI companies call this 'training data,' they dehumanize it. What we're talking about is people's work -- their writing, their art, their music," he said.

Last year, authors including John Grisham, Jodi Picoult and George RR Martin sued OpenAI for "systematic theft on a mass scale."

Hollywood stars including Pedro Pascal, Jane Fonda and Mark Hamill last month backed a sweeping AI safety bill in California that was ultimately vetoed by Governor Gavin Newsom.

Other artists have chosen to collaborate with AI.

Facebook owner Meta last week announced that Hollywood actor Casey Affleck and horror studio Blumhouse were partnering to test its AI movie generating software by making a series of short films.

Among other famous signatories to Monday's statement were Radiohead singer Thom Yorke, author James Patterson and actor Kevin Bacon.