OpenAI, the influential artificial intelligence company that ousted and then reinstated its high-profile CEO three months ago, faces a new drama: a lawsuit from Elon Musk, one of the richest men in the world and a co-founder of the AI lab.

Musk sued OpenAI and its CEO, Sam Altman, accusing them of breaching a contract by putting profits and commercial interests in developing AI ahead of the public good. A multibillion-dollar partnership that OpenAI developed with Microsoft, Musk said, represented an abandonment of a founding pledge to carefully develop AI and make the technology publicly available.

"OpenAI has been transformed into a closed-source de facto subsidiary of the largest technology company, Microsoft,” said the lawsuit filed Thursday in Superior Court in San Francisco.