Google said it had started testing the latest prototypes of its self-driving cars on Mountain View, California roads, with safety drivers aboard.

The prototypes will join Google's Lexus cars, which use the same self-driving software, the company said in a blog post on Thursday.

Google's self-driving Lexus RX450h sport utility vehicles have been in operation for several years.

Although the prototypes are designed to work without a steering wheel or pedals, safety drivers will have a removable steering wheel, accelerator pedal and brake pedal during the test phase in case they need to take over driving.

Earlier this month, Google launched a website specifically for the self-driving car. That came after increasing criticism by customers and consumer groups that the search giant was not providing enough information about the project.

Google has so far reported 12 accidents involving the prototypes. Injuries have been minor, the search giant has said, and accidents were mostly a result of human error by the drivers of the other cars involved. - Reuters