The US National Highway Traffic Safety Administration (NHTSA) has announced an investigation into Toyota RAV4 battery fires, media reports said.

According to thedetroitbureau.com, the federal investigators began their probe after nearly a dozen owners submitted complaints about their 2013-2018 model year RAV4 SUVs which caught fire. The problem could affect nearly 1.9m examples of what is now Toyota's best selling vehicle in the US.

An NHTSA preliminary report said the "12V battery B+ terminal shorts to the battery hold down frame which may result in the sudden loss of electrical power, vehicle stalling, and/or a fire originating in the engine compartment."

The report also said, in addition to the 11 complaints, the agency received "additional Early Warning Report (EWR) data alleging a non-crash thermal event originating in the left side of the engine compartment" of the affected vehicles, thedetroitbureau.com added.

"A majority of thermal events occurred during driving conditions with four taking place with the ignition off. Drivers experienced stalling prior to the thermal event in half of the instances where the vehicle was in motion. The 12 volt battery was identified as the area of origin in a majority of the incidents reviewed."

A US Toyota spokesman responded: "Toyota is aware that NHTSA has opened this investigation and we are cooperating with the agency."

NHTSA officials declined to comment on the investigation, referring TheDetroitBureau to its website.

The report added Toyota had not yet been asked to issue a recall on the vehicle, and federal officials didn't indicate how long they believe it will take to complete their investigation.

Toyota could voluntarily recall the vehicles to address the problem or the agency could compel them to do so. No fatalities or injuries have been reported related to the problem, thedetroitbureau.com added.