$Apple (AAPL.US)$ sued privately held ChatGPT parent OpenAI and one of its top executives Friday alleging the AI company stole trade secrets as part of its effort to develop competing devices.

The civil suit filed in the Northern District of California accuses OpenAI's chief hardware officer, Tang Tan, and Chang Liu, a member of its technical staff, of taking Apple's confidential information through various methods. Both are former Apple employees who went to work for OpenAI.

The lawsuit shows how the relationship between the two companies has rapidly deteriorated since 2024, when they signed a deal to have OpenAI's ChatGPT work with Apple's Siri chatbot. Apple's new Siri AI, announced in June, is powered by Gemini technology from $Alphabet-A (GOOGL.US)$.

Tan is leading OpenAI's efforts to develop its own devices, a crucial strategic effort so that the company can reach consumers directly, rather than via other companies' devices such as Apple's iPhone.

The suit alleges that Tan emailed himself information about Apple's suppliers and that he has directed job candidates still working for Apple to bring "actual parts" from Apple to their interviews for "show and tell" with the OpenAI team.

Apple accuses Liu of using a former colleague's work computer to access Apple's network, alleging that Liu downloaded "dozens of Apple's confidential hardware-related files." Liu coached the former colleague, whom he was recruiting to join OpenAI, on ways to "avoid trouble with the security team" when copying confidential files, the suit says.

Tan spent 24 years at Apple, rising to become a senior executive on its product design team. He worked closely with Jony Ive, Apple's head of industrial design. Tan left Apple to join Ive's AI device startup io Products, which subsequently merged with OpenAI.

The lawsuit doesn't name Ive.

OpenAI is facing other legal claims, including a trade-secrets suit brought by iyO, a startup developing a screenless, voice-controlled device worn in the ear. That company alleged last year that a former engineer stole files from the company and handed them over to Tan, then a senior executive connected to io Products.

OpenAI has denied any theft of iyO's ideas and said its device is different from the startup's product.

OpenAI also considered sending a breach of contract notice to Apple earlier this year, alleging that the iPhone maker didn't uphold the terms of their 2024 agreement to promote ChatGPT within Siri, according to a person familiar with the matter. Apple did not immediately respond to a request for comment.

Last month a California federal judge dismissed a lawsuit from Elon Musk's xAI that accused OpenAI of recruiting a former engineer to induce him to share information about the company's Grok chatbot.

Meanwhile, $New York Times (NYT.US)$ has sued $Microsoft (MSFT.US)$ and OpenAI over alleged theft of a different kind, accusing the technology companies in late 2023 of using its content without permission to create and train their AI products. The Times and other publishers asked a federal judge this week to levy sanctions against OpenAI, saying the company has withheld evidence during the legal proceedings.

The Wall Street Journal's parent company, News Corp, has a content deal with OpenAI.