A consortium of investors led by Elon Musk offered $97.4bn to take over OpenAI, the maker of ChatGPT.

The billionaire's attorney, Marc Toberoff, confirmed he submitted the bid for "all assets" of the tech company to its board on Monday.

The offer is the latest twist in a longstanding battle between Musk, the world's richest man and right hand to US President Donald Trump, and Open AI chief executive Sam Altman over the future of the start-up at the centre of the AI boom.

In response to the bid, Altman posted on Musk's social media platform X: "No thank you but we will buy Twitter for $9.74 billion if you want."

OpenAI is widely credited with helping bring artificial intelligence tools into the mainstream and sparking huge investment in the sector.

Musk and Altman co-founded the start-up in 2015 as a non-profit company, but the relationship has soured since the Tesla and X boss departed the firm in 2018.

Altman is said to be restructuring the company to become a for-profit entity, stripping it of its non-profit board - a move Musk argues means the company has abandoned its founding mission of developing AI for the benefit of humanity.

But OpenAI argues its transition into a for-profit firm is required to secure the money needed for developing the best artificial intelligence models.

The bid to take over OpenAI bid is being backed by Musk's AI company xAI, as well as several private equity firms, including Baron Capital Group and Valor Management.

"It's time for OpenAI to return to the open-source, safety-focused force for good it once was. We will make sure that happens," Musk said in a statement.

The offer tabled at $97.4bn is much lower than the $157bn the company was valued at in its latest funding round in October last year. Talks over a further funding round reportedly value it now at $300bn.

In a statement, Mr Toberoff said the consortium would be "prepared to consider matching or exceeding" any potential higher bid.

"As the co-founder of OpenAI and the most innovative and successful tech industry leader in history, Musk is the person best positioned to protect and grow OpenAI's technology," Musk's attorney added on his behalf and other investors.

The creator of ChatGPT is also teaming up with another US tech giant, Oracle, along with a Japanese investment firm and an Emirati sovereign wealth fund to build $500bn of artificial intelligence infrastructure in the US.

The new company, called The Stargate Project, was announced at the White House by President Donald Trump who billed it as "the largest AI infrastructure project by far in history" and said it would help keep "the future of technology" in the US.

Musk, despite being a top advisor to Trump, has claimed the venture does not "actually have the money" it has pledged to invest, though he has also not provided any details or substantiation for the comments.