The state of California is suing Tesla over allegations of operating a “racially segregated workplace” at its factory near San Francisco.

California’s department of fair employment and housing (DFEH) said it had filed a lawsuit alleging widespread discrimination and harassment of black employees following complaints from hundreds of Tesla workers at its main factory in Fremont.

“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,” Kevin Kish, the DFEH’s director, said in a statement.

The department claimed black Tesla workers were subjected to racist graffiti and racial slurs. The agency said it filed its lawsuit at on Alameda county superior court late on Wednesday, and would make the complaint available to the public on its website on Thursday.

In a blogpost pre-empting the announcement of the filing, Tesla described the lawsuit as “misguided” and said it would ask the court “to pause the case and take other steps to ensure that facts and evidence will be heard”.

Tesla said the DFEH had “declined to provide Tesla with the specific allegations or the factual bases for its lawsuit”.

“Attacking a company like Tesla that has done so much good for California should not be the overriding aim of a state agency with prosecutorial authority. The interests of workers and fundamental fairness must come first,” it said. “Tesla strongly opposes all forms of discrimination and harassment and has a dedicated employee relations team that responds to and investigates all complaints.”

Tesla was ordered by a Californian federal court last year to pay almost $137m (£101m) in damages to a black former employee who said he endured racial abuse while working at Fremont.

Owen Diaz, a former contracted elevator operator who worked at the plant between 2015 and 2016, alleged he was harassed and faced “daily racial epithets” including the “N-word”. He also said employees drew swastikas and left racist graffiti and drawings around the plant.

Diaz was awarded $6.9m in damages for emotional distress and $130m in punitive damages, in what is believed to be the largest such verdict of its kind.