Former OpenAI chief executive Sam Altman is to join Microsoft’s advanced AI research team after a weekend which saw him ousted by OpenAI and briefly appear to be negotiating a return to the company.

ChatGPT maker OpenAI announced on Friday it was removing Mr Altman, with a statement from its board saying it “no longer has confidence in his ability to continue leading OpenAI”.

However, reports emerged over the weekend suggesting Mr Altman was in discussions with OpenAI about quickly returning as chief executive, but these talks are said to have broken down.

Now, Microsoft boss Satya Nadella has confirmed that Mr Altman and OpenAI co-founder Greg Brockman – who also left the company on Friday – will be joining the tech giant “to lead a new advanced AI research team”.

“We look forward to moving quickly to provide them with the resources needed for their success,” Mr Nadella said in a post on X, formerly Twitter.

The reason for Mr Altman’s exit from the AI company remains unclear.

On Friday, OpenAI’s board said in a statement that he had not been “consistently candid in his communications” but did not offer any further details.

The statement said Mr Altman’s behaviour was hindering the board’s ability to exercise its responsibilities.

Mira Murati, OpenAI’s chief technology officer, was named as interim CEO effective immediately, the company said.

It was then reported on Saturday that the board had begun discussing Mr Altman’s return under pressure from investors and employees – some of whom were posting their support for Mr Altman on social media.

On Sunday, Mr Altman posted a picture of himself to X which showed him wearing a guest pass for OpenAI’s office alongside a message that it would be the “first and last time” he wore one.

But any talks over Mr Altman’s return broke down, with OpenAI now set to appoint former Twitch chief executive Emmett Shear as Mr Altman’s permanent replacement, a move Microsoft boss Mr Nadella also referred to in his post.

Microsoft has invested billions of dollars into the AI firm as part of a long-term “partnership” between the companies.

“We remain committed to our partnership with OpenAI and have confidence in our product roadmap, our ability to continue to innovate with everything we announced at Microsoft Ignite, and in continuing to support our customers and partners,” Mr Nadella said in his post.

“We look forward to getting to know Emmett Shear and OAI’s new leadership team and working with them.”

In a statement posted to X, Mr Shear said the role was a “once-in-a-lifetime opportunity”.

“I took this job because I believe that OpenAI is one of the most important companies currently in existence,” he said.

“When the board shared the situation and asked me to take the role, I did not make the decision lightly. Ultimately I felt that I had a duty to help if I could.”

Mr Shear added that the process and communication around Mr Altman’s removal as CEO had been “handled very badly”, trust in the company had been “seriously damaged”, and he pledged to hire an independent investigator to “dig into the entire process leading up to this point and generate a full report”.

He also said the OpenAI board did not remove Mr Altman over “any specific disagreement on safety” and that the board’s reasoning was “completely different from that”, but did not offer any further details on Mr Altman’s dismissal.