OpenAI has accused Apple of waging a “careless, aggressive and oddly personal lawsuit” in a blog post rebutting the iPhone maker’s claims that the AI start-up stole top-secret information.

“We do not have, nor want, any of their trade secrets,” the ChatGPT maker wrote on Monday evening, accusing Apple of “making vague accusations” and “trying to change their narrative.”

The post marks the latest escalation in a dispute that began last month when Apple filed a lawsuit claiming OpenAI had stolen hardware designs as it planned to launch its own AI-focused consumer devices.

The dispute comes as the two companies encroach on each other’s territory, with OpenAI venturing into consumer products and Apple joining forces with Google to revamp its Siri voice assistant.

OpenAI and Apple had previously partnered to integrate AI technology into Apple’s products. But the relationship began to sour after OpenAI last year acquired io, the design studio founded by former Apple design chief Sir Jony Ive, and hired a string of Apple employees.

Apple alleged in its lawsuit that more than 400 of its former employees now worked at OpenAI. It said it had received no response from OpenAI in February after contacting the start-up to warn it of an internal investigation into the potential theft of Apple’s trade secrets.

OpenAI said Apple’s lawyers had “emailed the wrong person after confusing two Asian last names” and “claimed they had a discussion with our General Counsel, which they now concede never happened.”