In the latest sign of bad blood between California and Tesla, the state’s civil rights regulator sued the electric-car maker late Wednesday night, alleging that “Tesla’s Fremont factory is a racially segregated workplace where Black workers are subjected to racial slurs and discriminated against in job assignments, discipline, pay and promotion.”

The California Department of Fair Employment and Housing said its lawsuit was sparked by hundreds of worker complaints, including one from a Black employee who heard racial slurs as often as 50 to 100 times a day and others who said workers flashed Confederate flag tattoos as a means of intimidation.

The department said other complaints alleged that “swastikas, ‘KKK,’ the n-word and other racist writing are etched onto walls of restrooms, restroom stalls, lunch tables and even factory machinery.”

Tesla, in a blog post published before the lawsuit was filed, said it will ask the court to pause the case. It also slammed the state for “attacking a company like Tesla that has done so much good for California,” noting that the Fremont factory “has a majority-minority workforce and provides the best paying jobs in the automotive industry to over 30,000 Californians.”

The lawsuit marks yet another rift between California and Tesla CEO Elon Musk, who early on in the pandemic defied COVID lockdown rules to keep the Fremont factory open and later moved himself and the company’s headquarters to Texas.

DFEH announced the lawsuit on Thursday, stating in the civil action in Alameda Superior Court that Tesla, Inc.,violated the Fair Employment and Housing Act and the California Equal Pay Act. The lawsuit alleges that Black workers are subjected to racial slurs by managers and supervisors, segregated to the lowest levels of the workforce, including the contracted workforce, and are severely under-represented in the ranks of executives, senior officials, and managers.

"After receiving hundreds of complaints from workers, DFEH found evidence that Tesla’s Fremont factory is a racially segregated workplace where Black workers are subjected to racial slurs and discriminated against in job assignments, discipline, pay, and promotion creating a hostile work environment,” said DFEH Director Kevin Kish. “DFEH will continue to take steps to keep workplaces free of harassment and racism."

In addition to race-based segregation in the terms and conditions of employment, DFEH alleges that Tesla has turned a blind eye to years of complaints from Black workers protesting the near-constant use of racial slurs and derogatory language in the workplace, and the presence of racist writing and graffiti in common areas of the workplace, including swastikas and other hate symbols.

In the Feb.9 post on Wednesday, entitled “The DFEH’s Misguided Lawsuit,” Tesla said it “strongly opposes” all forms of discrimination and harassment. The company denounced the lawsuit, arguing that the state agency had investigated dozens of previous claims in recent years and found no misconduct.

“It therefore strains credibility for the agency to now allege, after a three-year investigation, that systematic racial discrimination and harassment somehow existed at Tesla,” the company said. “A narrative spun by the [DFEH] and a handful of plaintiff firms to generate publicity is not factual proof.”

Tesla did not respond to media requests for comment.

Tesla also said the California agency had declined its requests for information on the accusations. The company plans to ask the court to “pause the case and take other steps to ensure that facts and evidence will be heard,” it added.

In October, a federal jury in San Francisco awarded $137 million to a Black former Tesla employee who said he had faced racial harassment from a supervisor and other colleagues while working at the Fremont factory in 2015 and 2016. Employees had drawn swastikas and scratched a racial epithet in a bathroom stall and left drawings of derogatory caricatures of Black children around the factory, he said.

The next month, Jessica Barraza, another Tesla employee, sued the company, accusing it of allowing pervasive sexual harassment, both verbal and physical. Six more women sued the company in December, citing similar treatment.

Last month, one of Tesla’s top Black executives, Valerie Capers Workman, left the company. As head of human resources at Tesla, Ms. Workman was often the face of its response to such suits.

The New York Times and CalMatters contributed to this report.