The boss of Microsoft has said there is “no OpenAI” without his company’s involvement, as he revealed the American tech behemoth was not consulted about the sacking of Sam Altman.

Satya Nadella said Microsoft, OpenAI’s biggest investor, was not contacted by OpenAI board members before they sacked Altman as chief executive on Friday. His comments came as OpenAI said it was in “intense discussions” to resolve its staff and leadership crisis, according to a report.

Speaking to the tech journalist Kara Swisher on her podcast, he said: “It’s not even the money and the capital. I mean, here’s a simple way to think about this. Sam chose Microsoft once. Sam chose Microsoft twice. Someone’s got to think about why? There is no OpenAI without, sort of, Microsoft leaning in, in a deep way, to partner with this company on their mission.”

Microsoft announced on Monday that it had hired Altman and OpenAI’s former president, Greg Brockman, who had resigned following his colleagues sacking, to a new AI unit.

Nadella told Swisher that Microsoft did not have “any relationship” with the non-profit board, which in turn governs a commercial subsidiary operated by Altman.

However, he added: “As a partner, I think it does deserve you to be consulted on the big decisions.”

OpenAI’s vice-president of global affairs, Anna Makanju, told staff on Monday that OpenAI management was in touch with Altman, the interim chief, Emmett Shear, and the board – “but they are not prepared to give us a final response this evening”, according to a memo seen by Bloomberg News.

“We are continuing to go over mutually acceptable options, and are scheduled to speak again tomorrow morning when everyone’s had a little more sleep,” Makanju wrote. “These intense discussions can drag out, and I know it can feel impossible to be patient.”

Staff at the San Francisco-based company are in open revolt against Altman’s removal. More than 700 of OpenAI’s 750 employees have signed a letter calling on the board to reinstate Altman and then resign.

In a further interview, Nadella called for changes in the way OpenAI is governed after the company behind the ChatGPT chatbot was plunged into turmoil by Altman’s abrupt ousting last week.

The four-person OpenAI board, which fired Altman on Friday and publicly accused him of failing to be “consistently candid in his communications”, remains under pressure to stand down. One of its members, OpenAI’s chief scientist, Ilya Sutskever, is a signatory to the letter calling on the board to resign.

In various interviews, Nadella made the case for change at OpenAI, which was founded as a non-profit entity, but later established a commercial subsidiary run by Altman.

“At this point, I think it’s very clear that something has to change around the governance,” Nadella told CNBC on Monday, adding that Microsoft would have “a good dialogue with their board on that”.

He stressed that whether OpenAI employees stay on in their current roles or move to Microsoft was a choice for them. “I’m open to both options,” he said.

Just a day after announcing Altman would be joining Microsoft, Nadella raised the prospect that Altman might not end up directly working for the tech giant after all. “Irrespective of where Sam is, he’s working with Microsoft,” he told Bloomberg.

In their letter on Monday, hundreds of employees at the startup urged its board to reconsider its decision. “We, the undersigned, may choose to resign from OpenAI and join the newly announced Microsoft subsidiary run by Sam Altman and Greg Brockman,” they wrote. “We will take this step imminently, unless all current board members resign … and [reinstate] Sam Altman and Greg Brockman.”

Altman has been using social media in recent days to express gratitude to those at OpenAI who have been posting the same message, that the company “is nothing without its people”, on their profiles.

In a post on X, formerly Twitter, on Monday, he wrote: “Satya and my top priority remains to ensure OpenAI continues to thrive. We are committed to fully providing continuity of operations to our partners and customers. The OpenAI/Microsoft partnership makes this very doable.”