Ilya Sutskever, OpenAI’s co-founder and chief scientist, has left the artificial intelligence start-up six months after moving against its chief executive Sam Altman in a shock coup that ultimately proved unsuccessful.

“After almost a decade, I have made the decision to leave OpenAI,” Sutskever wrote in a post on social media site X on Tuesday. “The company’s trajectory has been nothing short of miraculous, and I’m confident that OpenAI will build AGI [artificial general intelligence] that is both safe and beneficial.”

The San Francisco start-up commands a valuation of more than $80bn, thanks in part to a major partnership with Microsoft. Both OpenAI and Google — its chief competitor in AI — have released cutting-edge updates to their models this week, which have pushed the frontier of the technology.