Google will release monthly reports on the performance of its self-driving cars, and it disclosed summaries of the 12 accidents that involved the vehicles. Google described all of the accidents as minor, saying no injuries were reported. The company said Friday, as it has in the past, that the self-driving technology was not to blame for any of the accidents. In one case, however, an employee used the self-driving car to run an errand and rear-ended another car that was stopped in traffic. Google had previously disclosed that accident, which happened in August 2011. The advocacy group Consumer Watchdog has pushed Google to release the accident reports, and it said Friday that the reports themselves still need to be released because more details are needed and Google is asking the public to take its word. The Associated Press has asked Google and the California Department of Motor Vehicles for the reports. Both have refused, citing privacy concerns. Google Inc. started testing the cars in 2009, and the first accident was in May 2010. The company says six of the accidents happened while the car was in autonomous driving mode. The other six happened while staffers were driving, including one incident where the car was hit by another driver who rolled through a stop sign. Google says the self-driving car automatically applied the brakes when it detected the other vehicle, and Google’s driver took manual control once the brakes were applied. The Google vehicle sustained some damage. While several of the accidents happened at low speeds or while the car was stopped, in one case a Google vehicle was driving 63 miles per hour on a highway in San Jose when another vehicle veered into its side. According to Google, the cars have been involved in four accidents this year. The Mountain View, California-based company says the cars travel about 10,000 miles a week on public streets. The vehicles have driven about one million miles in autonomous mode and Google’s drivers have been in control for 800,000 additional miles.