Around 500 employees at OpenAI have signed a letter demanding the company’s board resigns and reinstates dismissed chief executive Sam Altman, it has been reported.

According to Wired, staff at the AI firm behind ChatGPT who have signed the letter have threatened to quit and join Mr Altman in his new venture at Microsoft unless he is allowed to return to the company.

The report says the letter claims the board’s decision to remove Mr Altman and co-founder Greg Brockman has jeopardised the company’s work and accuses the board of not having the competence to oversee the company.

It calls for the board to resign and be replaced by two new lead independent directors, and adds that if their demands are not met, those who have signed the letter may choose to resign from the company and join Mr Altman and Mr Brockman in their new AI research team at Microsoft – which announced Mr Altman would be joining the company on Monday.

According to reports, the letter has been signed by several senior members of staff at OpenAI, including Ilya Sutskever, the company’s chief technology officer and one of the board members at the centre of the decision to initially remove Mr Altman.

Mr Sutskever has since posted to X, formerly Twitter, that he “deeply regrets” his participation in the board’s action and that he would “do everything I can to reunite the company”.

The demands from staff continue an extraordinary few days for the company, which announced the shock decision to dismiss Mr Altman on Friday, with the board saying in a statement it “no longer has confidence in his ability to continue leading OpenAI”, but not revealing any specific reasons for his dismissal.

However, reports emerged over the weekend suggesting Mr Altman was in discussions with OpenAI about quickly returning as chief executive, but these talks were said to have broken down on Sunday, before Microsoft – OpenAI’s largest investor – announced Mr Altman was joining a new advanced AI research team at the company in a post on Monday morning.

OpenAI has since offered the chief executive role to former Twitch boss Emmett Shear, who said he had agreed to join the company.

A number of OpenAI staff took to social media on Monday to post the same message: “OpenAI is nothing without its people”, in a first sign of ongoing discontent inside the firm.