Federal authorities are investigating the safety of electric vehicles, after a third fire involving a General Motor's Chevy volt was reported.

U.S. auto safety regulators have asked makers of electric vehicles about their lithium-ion batteries' risk of catching fire, according to a Bloomberg report Saturday citing four people familiar with the investigation.

Lithium-ion batteries are the latest technology used by automakers such as GM, Nissan Motor Co., Ford Motor Co., Tesla, to power their electric models.

But in reaction, GM stands by its vehicle assuring the Volt is a safe car.

"NHTSA has stated that based on available data, there's no greater risk of fire with a Volt than a traditional gas-powered car," GM's chief engineer Jim Federico, told Bloomberg in a statement.

Lithium-ion batteries can catch fire if their case is pierced by steel or another metal. That damage causes an internal chemical reaction that can result in a fire days or weeks after, Bloomberg notes.

The latest case of fire reported occurred in June in a Chevrolet Volt that had been crash-tested by the National Highway Traffic Safety Administration.

Three weeks later the Volt caught fire in a storage at the National Highway Traffic Safety Administration, perhaps after the battery suffered damage.