OpenAI co-founder Sam Altman will return as CEO just days after he was fired by the board, the firm has said.

The agreement "in principle" involves a new board being installed, the tech company added.

It comes after Mr Altman was sacked on Friday triggering an open letter from staff who threatened to resign unless he was reinstated.

"I am looking forward to returning to OpenAI," Mr Altman said in a post on social media.

He added: "I love OpenAI, and everything I've done over the past few days has been in service of keeping this team and its mission together.

"I'm looking forward to returning to OpenAI, and building on our strong partnership with Microsoft."

In addition to Mr Altman's return, OpenAI agreed in principle to partly reconstitute the board of directors that had dismissed him.

The initial board will constitute former Salesforce co-CEO Bret Taylor, former US treasury secretary Larry Summers, and Quora CEO and current director Adam D'Angelo, OpenAI said.

This breaking news story is being updated and more details will be published shortly. Please refresh the page for the fullest version.

OpenAI said the move followed a "deliberative review process by the board", which concluded Mr Altman "was not consistently candid in his communications with the board".

The statement said his behaviour was hindering the board's ability to exercise its responsibilities.

But now reports suggest he could be making a swift comeback to the company he helped form.