June 24 (Reuters) - A federal judge in San Francisco

ruled late Monday that Anthropic's use of books without

permission to train its artificial intelligence system was legal

under U.S. copyright law.

Siding with tech companies on a pivotal question for the AI

industry, U.S. District Judge William Alsup said Anthropic made

"fair use" of books by writers Andrea Bartz, Charles Graeber and

Kirk Wallace Johnson to train its Claude large language model.

Alsup also said, however, that Anthropic's storage of the

authors' pirated books in a "central library" violated their

copyrights and was not fair use.

(Reporting by Blake Brittain in Washington; Editing by Chizu

Nomiyama )