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.

Apple and OpenAI have "locked up markets to maintain their monopolies and prevent innovators like X and xAI from competing," the lawsuit said.

The complaint said Apple and OpenAI conspired to suppress xAI's products, including on the Apple App Store. "If not for its exclusive deal with OpenAI, Apple would have no reason to refrain from more prominently featuring the X app and the Grok app in its App Store," xAI said.

Apple and OpenAI did not immediately respond to requests for comment.

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

Apple’s partnership with OpenAI has integrated its AI platform ChatGPT into iPhones, iPads and Macs.

Musk's xAI acquired X in March for $33 billion to enhance its chatbot training capabilities. Musk also has integrated the Grok chatbot into vehicles made by his electric automobile company Tesla (TSLA.O), opens new tab.

Musk's xAI was launched less than two years ago and competes with Microsoft-backed (MSFT.O), opens new tab OpenAI as well as with Chinese startup DeepSeek.

Musk is separately suing OpenAI and its chief executive Sam Altman in federal court in California to stop its conversion from a nonprofit to a for-profit business. Musk cofounded OpenAI with Altman in 2015 as a nonprofit.

Apple’s App Store practices have been the focus of multiple lawsuits. In one ongoing case by “Fortnite” video game maker Epic Games, a judge ordered Apple to allow greater competition for app payment options.