San Francisco, June 18 : SpaceX which fired employees who wrote a letter criticising Elon Musk's behaviour in the public sphere has likely violated US labour laws. According to The Verge, labour lawyers now say the firings may have violated US labour law. The fired employees may also approach the National Labor Relations Board (NLRB) to sue SpaceX. "To be covered, an action has to be concerted (certainly the case here) and it has to relate to working conditions," Charlotte Garden, a law professor at Seattle University, was quoted as saying in the report late on Friday. SpaceX on Thursday fired employees who wrote an open letter against Musk's behaviour on Twitter, calling it a "frequent source of distraction and embarrassment" for them. "As our CEO and most prominent spokesperson, Elon is seen as the face of SpaceX, every Tweet that Elon sends is a de facto public statement by the company. It is critical to make clear to our teams and to our potential talent pool that his messaging does not reflect our work, our mission, or our values," the SpaceX employees wrote. According the reports, the the case is successful, "SpaceX could be forced to reinstate the fired employees with back pay". Recently, the NLRB ordered Musk-run Tesla to reinstate a fired employee with back pay. The Communications Workers of America (CWA) has taken the SpaceX firings seriously. "Elon Musk says he's committed to free speech - except when his employees are exercising their legally protected right to speak out about their working conditions," the CWA said in a statement. Meanwhile, SpaceX President Gwynne Shotwell criticised the open letter as "overreaching activism". "The letter, solicitations and general process made employees feel uncomfortable, intimidated and bullied, and/or angry because the letter pressured them to sign onto something that did not reflect their views," wrote Shotwell. "We have too much critical work to accomplish and no need for this kind of overreaching activism," she added. /IANS