OpenAI, the company that launched ChatGPT a year ago, said Friday it had dismissed CEO Sam Altman in a shock firing of a central figure in the AI revolution.

Altman, 38, became a tech world sensation with the release of ChatGPT, an artificial intelligence chatbot with unprecedented capabilities, churning out human-level content like poems or artwork in just seconds.

He quickly rose to become Silicon Valley's newest star, traveling the world to meet with political leaders and huge audiences fascinated by the promise and threats of AI.

His dismissal caught the tech world completely by surprise, with rumors rife on social media on what had caused the sudden sacking.

OpenAI's board said in a statement that Altman's departure "follows a deliberative review process," which concluded "he was not consistently candid in his communications with the board, hindering its ability to exercise its responsibilities."

"The board no longer has confidence in his ability to continue leading OpenAI," it concluded.

In a post on X, Altman said he "loved my time at OpenAI."

"It was transformative for me personally, and hopefully the world a little bit."

He said he would have "more to say about what's next later."

The launch of ChatGPT ignited a race in AI -- hailed as the next big chapter in technology -- with contenders including tech giants Amazon, Google, Microsoft and Meta.

Microsoft has invested billions of dollars in OpenAI and has woven the company's technology into its offerings, including search engine Bing.

Google, caught off guard, moved quickly to push out its own AI offerings, including the chatbot Bard.

Altman has testified before US Congress about AI and spoken with heads of state about the technology, as pressure ramps up to regulate against risks such as AI's potential use in bioweapons, misinformation and other threats.

The statement said the board was "grateful for Sam's many contributions to the founding and growth of OpenAI. At the same time, we believe new leadership is necessary as we move forward."

Altman would be replaced on an interim basis by Mira Murati, the company's chief technology officer, the statement said.

"We have a long-term partnership with OpenAI and Microsoft remains committed to Mira and their team as we bring this next era of AI to our customers," a Microsoft spokesperson said in a statement to AFP.

'Lots of empathy' 

OpenAI's board of directors consists of OpenAI chief scientist Ilya Sutskever, Quora CEO Adam D'Angelo, technology entrepreneur Tasha McCauley, and Georgetown Center for Security and Emerging Technology's Helen Toner.

The statement added that Greg Brockman, a close associate of Altman's, would step down as chairman of the board, but stay at the firm, reporting to the new CEO.

Altman earlier this month led a major developer's conference for OpenAI, announcing a new set of products that were largely met positively in Silicon Valley.

The young executive on Thursday told AFP he understood some of the worries over AI and its disruptive powers.

"(I have) lots of empathy for why anyone would feel, however they feel, about this," he said of the platform that is credited with launching the revolution in generative artificial intelligence.

Altman was speaking on the sidelines of the annual Asia-Pacific Economic Cooperation (APEC) summit in San Francisco where he was swarmed by fans after his appearance, many of whom wanted to take selfies with him.