Tesla CEO Elon Musk has rejected claims that workers for the electric car manufacturer are underpaid and overworked, suggesting a union was deliberately agitating the firm.  

Jose Moran, who says he worked at Tesla’s plant in Fremont, California, for the past four years, posted an article on Medium on Thursday titled ‘Time for Tesla to Listen.’ He cites low pay, as well as “injuries, poor morale, unfair promotions, high turnover, and other issues.”

Moran wrote: “Many of us have been talking about unionizing, and have reached out to the United Automobile Workers (UAW) for support…But at the same time, management actions are feeding workers’ fears about speaking out.”

In response, Musk suggested Moran was on the payroll of the UAW union and was deliberately trying to provoke unrest, calling Moran’s claims “morally outrageous.”

Musk told the website Gizmodo on Thursday: “Our understanding is that this guy was paid by the UAW to join Tesla and agitate for a union. He doesn’t really work for us, he works for the UAW.”

He added: “Tesla is the last car company left in California, because costs are so high. The UAW killed NUMMI and abandoned the workers at our Fremont plant in 2010. They have no leg to stand on.”

In response to claims about low wages, Musk said Tesla’s starting wage was higher than those unionized in the UAW, stating: “Total compensation is higher for a given level of seniority when factoring in stock grants.”

On Friday, UAW denied that Moran works for the union, saying “[Moran] is not and has not been paid by the UAW.”