PHOENIX, Arizona: Tesla has received the green light to test autonomous robotaxis in Arizona, expanding its efforts to roll out a driverless ride-hailing service across the United States.

The Arizona Department of Transportation said that it approved Tesla's application, filed in June, to run trials in the Phoenix metro area with safety drivers on board.

The company did not immediately respond to a request for comment, and the department did not specify when the trials would begin or how long they would run.

CEO Elon Musk has said Tesla aims to launch an autonomous ride-hailing service by the end of this year that will cover about half of the U.S. population.

Tesla began limited robotaxi testing in Austin, Texas, in June. The company operated around a dozen vehicles for a small group of passengers. Those trials also required safety monitors in the front seat and restricted where the cars could operate.