One of Google's self-driving cars was reportedly involved in a minor accident near the company's Mountain View, Calif., headquarters late last week, causing some critics to question the reliability of the high-tech vehicles.

However, in an ironic twist, Google has claimed that the car was not actually driving itself at the time of the collision, but was instead was being controlled by a human who was using the vehicle's manual setting.

The Auto blog Jalopnik broke the news on Monday after posting pictures of the accident that were snapped by a tipster. The photos show a Prius - recognizable as a Google car by the roof equipment stowed on top that resembles the device used by a typical Google Streetview image collector - pulled over on the side of a roadway after reportedly rear-ending another Prius.

Google's self-driving vehicles use a combination of radar, video cameras and lasers to safely navigate through traffic. Although the ultimate goal is to develop cars that can completely operate without human input, self-driving cars must legally have a person behind the wheel to take control of the vehicle if anything goes wrong.

Although Google has acknowledged the accident occurred, the company used the event to emphasize how computer-controlled cars could potentially drastically decrease the rate of auto collisions.

"Safety is our top priority. One of our goals is to prevent fender-benders like this one, which occurred while a person was manually driving the car," said a company spokesperson, adding that up to this point Google's self-driving cars have traveled more than 160,000 miles autonomously without incident.

Stanford University robotics professor Sebastian Thrun, a project leader on the Google initiative, argues that self-driving cars would be considerably safer as most accidents are caused by human error, and not a technical malfunction. In a speech at the TED 2011 conference earlier this year, Thrun discussed how computer-controlled vehicles could also make U.S. highways more efficient.

"Do you realize that we could change the capacity of highways by a factor of two or three if we didn't rely on human precision on staying in the lane but on robotic precision, and thereby drive a little bit closer together on a little bit narrower lanes and do away with all traffic jams on highways?" he said.

In June, Nevada became the first state in the nation to pass legislation legalizing driverless vehicles after some quiet lobbying for the measure on Google's end. The state Department of Motor Vehicles has until March 1, 2012 to develop a series of regulations surrounding all aspects of ownership and operation of the cars, such as insurance standards.

The U.S. isn't the only nation working to popularize the notion of self-driving vehicles. Last year, the European Commission announced it is funding a project known as the Safe Road Trains for the Environment (SARTRE), which aims to develop a wireless infrastructure that allows cars traveling on a public highway to join a semi-autonomous "road train" of vehicles that contain one professional driver at the helm operating all the automobiles in the platoon.

Google Robotics