Tesla’s billionaire chief executive Elon Musk tweeted a denial that the car involved in a fatal crash in Texas last week had its Autopilot mode enabled.
Mr Musk, who co-founded Tesla in 2003, also said the owner of the car had not purchased the Full Self-Driving (FSD) package that offers users enhanced Autopilot capabilities.
“Data logs recovered so far show Autopilot was not enabled & this car did not purchase FSD,” Mr Musk said.
“Moreover, standard Autopilot would require lane lines to turn on, which this street did not have.”
On Saturday, a Tesla 2019 Model S crashed into a tree in Houston and burst into flames, killing two passengers.
Officials said the car appeared to have been driving itself at the time of the crash, according to media reports.
US road safety agency the National Highway Traffic Safety Administration and the National Transportation Safety Board (NTSB), which investigates civilian transportation crashes, are also probing the case.
The NHTSA said it is working with local law enforcement officers and will “take appropriate steps” after gathering more information.
"NTSB investigation will focus on the vehicle’s operation and the post-crash fire," NTSB said.
Following the accident, shares in Tesla dropped 3.4 per cent on Monday to $714.30 a share, shaving more than $5.5 billion off Mr Musk’s wealth. Mr Musk owns about 22.4 per cent of the company’s shares.
On Sunday, hours after the crash, he said on Twitter that a Tesla with the Autopilot system engaged is almost 10 times less likely to be involved in an accident than an average vehicle.
Tesla sells its automated driving systems under two brand names – Autopilot and FSD. All new Tesla cars come with the Autopilot driver-assist feature as standard and the company sells the more advanced FSD as an extra for almost $10,000.
Autopilot allows the car to steer, accelerate and brake automatically for other vehicles and pedestrians within its lane. FSD offers more enhanced features such as auto-parking and automatic lane changes while driving on the highway.
However, the company said the “currently enabled features require active driver supervision and do not make the vehicle autonomous”.
In the first quarter of this year, Tesla registered one accident for every 6.74 million kilometres driven with Autopilot engaged.
The company recorded one accident for every 3.29 million km when Autopilot was not engaged but other active safety measures were switched on.
Last month, the NHTSA said it had opened 27 investigations into crashes involving Tesla vehicles.