SpaceX has committed US$2 billion to xAI as part of a US$5 billion equity round, deepening the ties between tech billionaire Elon Musk's ventures as his artificial intelligence start-up races to compete with rival OpenAI, the Wall Street Journal reported on Saturday.

The investment follows xAI's merger with X and values the combined company at US$113 billion, with the Grok chatbot now powering Starlink support and eyed for future integration into Tesla's Optimus robots, the report added.

SpaceX and xAI did not immediately respond to Reuters' requests for comment.

Despite recent controversies involving Grok's responses, Musk has called it "the smartest AI in the world," and xAI continues to spend heavily on model training and infrastructure. (Reuters)