The National Labor Relations Board on Thursday filed a complaint against Tesla Inc., and said it is investigating the electric-car company for allegedly intimidating and harassing union organizers.

Some employees at Tesla’s auto plant in Fremont, Calif., have reportedly been working for almost a year with the United Auto Workers in an effort to form a union — a move Tesla management is opposed to.

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The workers’ complaints were filed with the NLRB in April but date back to a series of events ranging from November to March. According to NLRB documents, workers distributing union literature were told by security to leave the premises, employees were surveilled and “interrogated,” and managers attempted to prohibit workers from discussing union activities. Workers also complained of being forced to sign an “overly broad” confidentiality agreement “that coerces and intimidates employees from freely exercising their rights.”

In a letter to Tesla dated April 18, the NLRB warned that because of the nature of the alleged unfair labor practices, an injunction against the company may be appropriate.

Tesla strongly denied the allegations late Thursday, calling the them “baseless” and an attempt “to discredit Tesla publicly in the media.”

“These allegations, which have been filed by the same contingent of union organizers who have been so outspoken with media, are entirely without merit. We will obviously be responding as part of the NLRB process,” a Tesla spokesperson said.

A hearing on the NLRB complaint will be held Nov. 14 in Oakland, Calif.

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Separately, the San Francisco Chronicle on Thursday reported that some Tesla employees at the Fremont plant have complained that they did not receive proper training to handle hazardous materials and have suffered physical reactions as a result. A Tesla spokesperson told the Chronicle the claims were “completely false” and suggested union organizers were spreading misinformation.