US carmaker Tesla Inc on Monday was hit with a class-action lawsuit claiming its California production plant is a “hotbed for racist behaviour”. The lawsuit filed in California state court in Oakland is at least the third filed this year by black workers who say they were addressed using racial slurs and that the company ignored their complaints. But Monday’s lawsuit, filed by former Tesla employee Marcus Vaughn, is the first to bring those claims on behalf of a large class of black workers at the automaker’s Fremont, California factory. Tesla did not respond to a request for comment. The company is also facing lawsuits accusing it of discrimination against gay and older workers. It has denied those claims. Vaughn in the lawsuit says he was routinely called the “N-word” by supervisors and co-workers after he began working at the factory in April. He says he complained in writing to human resources officials, but the company never investigated his claims. Vaughn says he was fired in October for “not having a positive attitude”. He is seeking unspecified damages under a California anti-discrimination law. The growing number of discrimination lawsuits against Tesla come as the company is also facing a unionisation campaign from the United Auto Workers. In February, Tesla chief executive Elon Musk told the website Gizmodo that an employee who wrote a blog post criticising the company was “paid by the UAW to join Tesla and agitate for a union”. The union and the worker denied that he had been paid by UAW. Last month, the union filed a complaint with a federal labour board on behalf of scores of workers who it says were laid off because they support the union. The company denied the claims and said the decision was based on employee performance reviews.