SpaceX, xAI and the Pentagon's defence innovation unit did not immediately respond to requests for comment on Monday. Reuters could not independently verify the report.
Texas-based SpaceX recently acquired xAI in a deal that combined Musk's major space and defence contractor with the billionaire entrepreneur's artificial intelligence startup. It occurred ahead of SpaceX's planned initial public offering this year.
Musk's companies are reportedly among a select few chosen to participate in the $US100 million ($A141 million) prize challenge initiated in January, according to the Bloomberg report.
The six-month competition aims to produce advanced swarming technology that can translate voice commands into digital instructions and run multiple drones, the report said.
Musk was among a group of AI and robotics researchers who wrote an open letter in 2015 that advocated a global ban on "offensive autonomous weapons", arguing against making "new tools for killing people".
The US Defense Secretary last year outlined a new strategy to accelerate drone development and deployment by aiming to cut bureaucracy and boost domestic drone manufacturing.
The US also has been seeking safe and cost-effective ways to neutralise drones, particularly around airports and large sporting events - a concern that has become more urgent ahead of the FIFA World Cup and America250 anniversary celebrations this northern summer.
OpenAI, Alphabet's Google, Anthropic and xAI last year won contracts that are worth up to $US200 million ($A283 million) each and aimed at scaling up adoption of advanced AI capabilities in the Pentagon.
