Apple’s former chief designer Sir Jony Ive has joined OpenAI in a $6.5bn (£4.8bn) deal to challenge the iPhone.

OpenAI on Wednesday announced the takeover of io Products, a San Francisco start-up founded by Sir Jony and a group of other ex-Apple designers just last year.

The takeover paves the way for Sir Jony, the Briton famed for designing some of Apple’s most iconic products, to create a new generation of devices that could challenge the iPhone as the dominant piece of modern hardware.

Sir Jony seemingly took aim at his previous employer when announcing the new deal, hitting out at the “legacy” products on the market and the “decades old” technology within them.

Sam Altman, OpenAI’s co-founder and chief, said that io was “formed with the mission of figuring out how to create a family of devices that would let people use AI to create all sorts of wonderful things.”

Apple shares fell by more than 2pc after the announcement.

Sir Jony was Apple’s chief designer between 1992 and 2019. He was behind products including the iPhone, Apple Watch and iPad, and was described by Steve Jobs as his “spiritual partner” at the company.

The Briton founded io with the backing of Laurene Powell Jobs, the widow of Apple’s co-founder, and has recruited a team of engineers from the Californian tech giant, including his successor, Scott Cannon.

The team has already developed a prototype product based on AI. Mr Altman said: “Jony called one day and said: ‘This is the best work our team has ever done.’ I mean, Jony did the iPhone, Jony did the MacBook Pro. These are like the defining ways people use technology. It’s hard to beat those things. Those are really wonderful.”

He claimed the prototype was “the coolest piece of technology that the world will have ever seen.” Mr Altman added: “AI is such a big leap forward in terms of what people can do that it needs a new kind of computing form factor to get the maximum potential out of it.”

Sir Jony said: “People have an appetite for something new, which is a reflection on a sort of an unease with where we currently are.”

The announcement will ramp up the pressure on Apple, which has been struggling to navigate both the shift to AI and Donald Trump’s trade war.

The company’s shares have plunged 19pc since the start of the year amid fears about the impact of tariffs on China, where many of its devices are assembled, and concerns about the slow speed of its product development.

While Apple was one of the first tech companies to embrace AI with its voice assistant Siri, rivals have rapidly overtaken it in recent years. Although it licenced ChatGPT last year and promised a radically improved Siri, Apple has struggled to make a success of it.