Tesla is being investigated by the US government after reports that the firm's self-driving cars had broken traffic laws, including driving on the wrong side of the road and not stopping for red lights.

It said it was aware of 58 reports where the electric cars had committed such violations, according to a filing from the National Highway Traffic Safety Administration (NHTSA).

An estimated 2.9 million cars equipped with full self-driving tech will fall under the investigation.

Tesla, whose boss Elon Musk recently became the world's first half-trillionaire, has been approached for comment.

The NHTSA's preliminary evaluation will "assess the scope, frequency, and potential safety consequences" of the "Full Self-Driving (Supervised)" mode.

In this mode - which costs extra for Tesla owners - the cars can make lane changes and turns, but drivers must always be alert to take over at any time.

According to the NHTSA report, there were six crashes caused by cars stopping at a traffic light before setting off while the light was still red.

Four of the crashes resulted in injuries.

The traffic authority said Tesla had taken action "to address the issue" of cars going through red lights at a particular intersection in Maryland, where the problem repeatedly occurred.

The agency will also investigate reports of vehicles going into the opposite lane when making a turn.

It said some of the reported incidents gave "little notice to a driver or opportunity to intervene".

Tesla is already facing an investigation from the NHTSA over the cars' door locking mechanisms, after cases where children were reportedly trapped inside Model Y cars.

In some instances, car owners chose to smash the windows to let them out.

Tesla recently unveiled cheaper models of two of its most popular cars, as it tries to compete with cheaper electric vehicles often made by Chinese companies.

Its boss Elon Musk was formerly a close ally of President Donald Trump before a public falling-out earlier in the year.

In July, he announced the formation of a new political party, the America Party, in an attempt to rival the Republicans and Democrats.