Elon Musk has sued OpenAI and its chief executive Sam Altman, among others, accusing them of breaching contractual agreements made when he helped found the ChatGPT-maker in 2015, according to a lawsuit filed on Thursday in San Francisco.

The lawsuit said Altman, along with OpenAI’s co-founder Greg Brockman, originally approached Musk to make an open source, non-profit company that would develop artificial intelligence technology for the “benefit of humanity”.

The Microsoft-backed company’s focus on seeking profits breaks that agreement, lawyers for Musk said in the lawsuit.

OpenAI, Microsoft and Musk did not immediately respond to Reuters requests for comment.

Musk co-founded OpenAI in 2015, but stepped down from the company’s board in 2018. He also runs the electric vehicle maker Tesla and bought Twitter for $44 billion in October 2022.

ChatGPT, the chatbot from OpenAI, became the fastest-growing software application in the world within six months of its launch in November 2022. It also sparked the launch of rival chatbots from Microsoft, Alphabet and a bevy of startups that tapped the hype to secure billions in funding.

Since its debut, ChatGPT has been adopted by companies for a wide range of tasks from summarizing documents to writing computer code, setting off a race amongst Big Tech companies to launch their own offerings based on generative AI.