Apple has filed a lawsuit against OpenAI, accusing the ChatGPT maker of stealing confidential trade secrets while developing its own artificial intelligence hardware, marking a major escalation in tensions between the two companies.

The lawsuit, filed Friday in a federal court in California, alleges that OpenAI encouraged Apple employees it was recruiting to share confidential company information and even advised them on how to avoid attracting attention when leaving Apple.

"This case is about Apple's former employees stealing Apple's trade secrets for the benefit of OpenAI," Apple said in the court filing, adding that it filed the lawsuit to stop the alleged misuse of its proprietary information.

The lawsuit also names two former Apple employees who now work at OpenAI.

One of them is Tang Tan, who played a key role in designing the iPhone, Apple Watch and iPod before becoming OpenAI's chief hardware officer. The other is Chang Liu, who worked on Apple's product development before joining OpenAI earlier this year.

OpenAI said it is reviewing the lawsuit. Company spokesperson Drew Pusateri said OpenAI has "no interest in other companies' trade secrets" and remains focused on developing technology that benefits users.

Apple claims OpenAI's hardware project relies partly on confidential information taken from the company. Although OpenAI has not revealed details of the device it is developing, it has said the goal is to create a new way for people to interact with artificial intelligence beyond traditional computers and smartphones.

According to the lawsuit, Apple launched an internal investigation after suspecting that confidential information had been compromised and found what it described as a pattern of trade secret theft involving former employees who later joined OpenAI.

The complaint alleges that Liu accessed and downloaded confidential hardware-related files on an Apple-issued device after leaving the company. It also claims Tan encouraged Apple employees interviewing for jobs at OpenAI to bring actual Apple hardware components to interviews.

Apple said it raised its concerns with OpenAI in February but did not receive a response.

An Apple spokesperson said the company would continue to protect its employees' work and innovations through appropriate legal action.

The lawsuit comes as relations between the two companies have shifted from partnership to growing competition.

Apple partnered with OpenAI in 2024 to integrate ChatGPT into the iPhone, allowing users to access AI-powered responses when Siri could not answer their questions.

Since then, OpenAI has expanded its hardware ambitions by hiring former Apple designer Jony Ive to lead the development of an AI-powered device that industry analysts believe could eventually compete with Apple's products.

Last year, OpenAI announced a confidential hardware collaboration with Ive and acquired io Products, a company co-founded by Ive, Tang Tan and others, in a deal valued at nearly $6.5 billion.

Apple's lawsuit also names io Products as a defendant.

The legal battle comes as OpenAI considers a future public stock market listing while facing growing competition in the AI sector from companies including Anthropic and Google.

Despite scaling back some business projects earlier this year to focus on ChatGPT, OpenAI has continued developing its consumer hardware. Chief Financial Officer Sarah Friar told The Associated Press in April that the company expects to introduce its first consumer hardware product later this year.