(Bloomberg) -- Elon Musk’s SpaceX agreed to settle a claim by the US labor board that the company illegally tried to stifle an employee’s speech with a warning not to discuss job conditions with co-workers.

A regional director of the US National Labor Relations Board determined that the aerospace company violated federal law by admonishing an employee not to talk to coworkers about working conditions they were discussing with human resources staff, agency spokesperson Kayla Blado said. 

The settlement resolves a complaint that was filed with the agency last September, accusing SpaceX of “reprimanding” an employee for engaging in collective action “involving opposition to offensive racial comments in the workplace.”

The case is one of several run-ins that Musk’s companies have had with the labor board in recent years. SpaceX also is fighting an August complaint by the US Justice Department that it discriminates against refugees looking for jobs at its rocket factory. The billionaire’s electric-car maker, Tesla Inc., was sued Thursday by the US Equal Employment Opportunity Commission over claims it created a hostile work environment for racial minorities at its California factory.

In the settlement, SpaceX has agreed to post a notice about workers’ rights at its facility in Redmond, Washington, and to electronically distribute it to employees, Blado said in an email. The Redmond facility develops satellites for the company’s Starlink broadband internet system.

SpaceX and its attorneys didn’t immediately respond to requests for comment. The company didn’t admit wrongdoing as part of the settlement.

Federal law protects the right of employees to communicate and organize about working conditions, with or without a union. The NLRB, which enforces that law, can order policies changed or fired workers reinstated, but lacks authority to make companies pay punitive damages or hold executives personally liable for violations. 

The agency is currently investigating a separate complaint filed by a former employee accusing SpaceX of firing nine people last year in retaliation for comments critical of Musk and the company’s culture. Some of those workers were authors of an open letter protesting “inappropriate, disparaging, sexually charged comments on Twitter” by Musk, according to the complaint. 

Musk’s social media company X, formerly Twitter, this year settled with a former employee who NLRB prosecutors had concluded was illegally punished for protesting its return-to-office mandate. 

In March, Tesla lost its appeals court challenge to an NLRB ruling that the company illegally fired an employee because of his union activism, and that a tweet from Musk constituted an illegal threat. A larger panel of judges on the US 5th Circuit Court of Appeals has agreed to hear the case.

©2023 Bloomberg L.P.