According to a federal filing on Monday, the National Highway Traffic Safety Administration (NHTSA) has rejected a 2019 plea to begin a formal inquiry into Tesla vehicle fires.

In October 2019, the agency began a formal assessment of a petition submitted on behalf of Tesla owners by California lawyer Edward C. Chen, who raised concerns about non-crash fires, including allegations of three incidents in China.

Model 3 | Tesla United Kingdom

The National Highway Traffic Safety Administration said in 2019 that it was looking into whether Tesla should have recalled 2,000 of its electric cars instead of delivering a software update to correct a potential fault that may lead to battery fires that year.

Tesla was accused of "using over-the-air software updates to disguise and cover up a potentially widespread and deadly issue with their vehicles' batteries," according to the petition.

"Tesla's examination of the non-crash fires in China could not establish a root cause or positively relate the instances to any design or manufacturing flaw conditions," according to the NHTSA's denial, which also stated that "non-crash battery fires in Tesla vehicles are unusual events."

A request for comment from Tesla was not immediately returned.

"No fires connected to the relevant condition have been observed worldwide since three fires in China and Hong Kong over a 48-day period from late-March to mid-May 2019," according to the NHTSA. It also stated that "no fires have occurred in the United States as a result of this issue."