US billionaire Elon Musk has threatened legal action against Apple, accusing it of violating antitrust rules by favoring OpenAI's ChatGPT app in app store rankings over the account of its smart assistant Grok, which is being developed by his company xAI.

Musk said in a post on the X platform, formerly Twitter, which he also owns, that Apple is acting in a way that makes it impossible for any AI company other than OpenAI to reach the first position in the App Store, and this is a clear violation of antitrust laws. xAI will take immediate legal action.

Musk has not provided evidence to back up his claims, while some X users pointed out that DeepSeek took the top spot in the App Store in January, long after Apple announced its partnership with OpenAI, which allows Siri's assistant to use ChatGPT to handle complex queries.