Tesla Inc has demanded a safety advocacy group take down videos of its vehicles running over child dummies when its driver assistant system was engaged, calling them "defamatory" and "misleading."

The group, the Dawn Project, has launched a nationwide TV campaign warning of alleged potential dangers of what Tesla calls "Full Self-Driving" (FSD) software, adding to public and regulatory scrutiny of the technology.

One of the videos posted by the group shows a Tesla vehicle with FSD software running over child-sized mannequins, and says "Tell Congress to Shut it Down."

In a Cease and Desist letter dated Aug. 11, Tesla said the Dawn Project and its founder "have been disparaging Tesla's commercial interests and disseminating defamatory information to the public." The letter was disclosed by the Dawn Project on Thursday.

Tesla threatened to take legal action, saying the tests in the videos are "likely fraudulent" and "misrepresent the capabilities of Tesla's technology."

The U.S. safety regulator has stepped up investigations of Tesla's Autopilot system following a series of crashes.

The company said its "FSD Beta," a test version of its new automated driving technology used by a limited number of consumers, "does recognize pedestrians, including children, and when utilized properly, the system reacts to prevent or mitigate a collision."

The Dawn Project was founded by Dan O'Dowd, a critic of Tesla's FSD system and a software entrepreneur in California who had run for the U.S. Senate.

The Dawn Project said its tests are "are completely legitimate and not deceptive," and called Tesla's letter "marketing propaganda."

Tesla did not immediately respond to a request for comment.