(Reuters) -Billionaire entrepreneur Elon Musk's artificial intelligence startup xAI sued Apple and ChatGPT maker OpenAI in U.S. federal court in Texas on Monday, accusing them of illegally conspiring to thwart competition for artificial intelligence.

Musk earlier this month had threatened to sue Cupertino, California-based Apple, saying in a post on his social media platform X that "Apple is behaving in a manner that makes it impossible for any AI company besides OpenAI to reach #1 in the App Store."