OpenAI has accused a former employee of stealing confidential material about an unreleased device and later passing some of it to Apple, sharpening a trade-secrets dispute between the two companies. In a court filing lodged on Wednesday, OpenAI alleged that the unnamed individual downloaded more than 100 highly confidential files to personal accounts before leaving to rejoin Apple, with the final file sent in June on his last working day.

According to the filing, the transferred material included detailed images of one or more unreleased devices, along with sensitive engineering and manufacturing data. OpenAI said the person had spent six months at the company after an earlier stint at Apple, and has since returned to the iPhone maker. It further claimed the former employee presented OpenAI's product plans to Apple's senior leadership, including its vice president of operations in Asia, and argued that Apple is now pushing harder into AI-enabled products with that information in hand.

Apple rejected the allegations. In a statement to CNN, the company said it had found no evidence to support the claims and pointed to strict policies designed to stop new hires using confidential information from previous employers. It added that it would work with OpenAI to remove any OpenAI data found on its systems, while accusing OpenAI of trying to distract from the original case.

That original case runs the other way. Apple sued OpenAI in July, alleging the AI company had taken Apple's trade secrets to build its own devices. It claimed that former Apple staff who moved to OpenAI downloaded confidential files, and that job candidates were encouraged to bring Apple parts to interviews. OpenAI has denied the claims, argued that Apple has failed to identify any stolen trade secrets, and sought to have the case dismissed. The new filing forms part of that same litigation.

The timing is pointed. This week Apple unveiled HomeView, described as its biggest move into the smart home market in nearly a decade, with a revamped Siri at the centre of its AI strategy. OpenAI, meanwhile, is working on its own AI-enabled device, reported to be a screen-free smart speaker, and last year brought on former Apple design chief Jony Ive and his firm, io, to lead design across the company.

Staff movement between the two is substantial. Engineers switch firms regularly in Silicon Valley, but Apple has said in a court filing that OpenAI has hired more than 400 of its former employees.