OpenAI is suing Elon Musk for unfair competition and interfering with its business relationships with investors and customers, escalating a legal battle between the ChatGPT maker and the billionaire who helped bankroll the artificial intelligence startup a decade ago.

Sam Altman-backed OpenAI has countersued Elon Musk citing a pattern of harassment by him and asked the judge to hold him responsible for the "damage he has already caused" to the company. The Tesla and SpaceX CEO had in August last year filed a lawsuit against OpenAI and others for shifting away from its founding mission to develop AI for the good of humanity and not seek corporate profit.