As workers in California seek to unionize, the United Auto Workers has accused the company of interrogating employees at its massive Gigafactory battery plant over union activities and subjecting them to “heightened supervisory scrutiny.”

The case represents the first record of alleged labor violations at Tesla’s battery factory in Nevada since earlier this year, when Tesla employees on job pay and work conditions at the automaker’s assembly plant in Fremont, California.

The unfair labor practice (ULP) charges were filed Nov. 15 with the National Labor Relations Board, an independent government agency that seeks to enforce U.S. labor laws. The ULP claim was amended due to a procedural matter and , the UAW said.

The filing echoes charges made in October by the UAW, which accused the company then of in the Fremont. The automaker denied those charges, saying, “No one at Tesla has ever or will ever have any action taken against them based on their feelings on unionization.”

Additionally, in August, , claiming the automaker “interrogated” Fremont employees earlier this year over union activities.

, obtained by Jalopnik through a Freedom of Information Act request, emanates from Nevada, where Tesla’s Gigafactory is located. The ULP claim was made on behalf of a Gigafactory worker over alleged violations that took place at the battery plant, the UAW confirmed.

The partially-redacted filing alleges the automaker has intimidated, surveilled, and interrogated Gigafactory employees who’ve engaged in legally-protected union activities.

Specifically, the filing alleges that Tesla violated Section 7 of the National Labor Relations Act. the provision makes it “unlawful for an employer to interfere with, restraint, or coerce employees in the exercise of their rights” to organize a union.

“For example, employers may not respond to a union organizing drive by threatening, interrogating, or spying on pro-union employees, or by promising benefits if they forget about the union,” . The definition of an “unfair labor practice” is further spelled out on the NLRB’s website, and includes creating “the impression that you are spying on employees’ union activities,” promising “employees benefits if they reject” a union, and conveying “the message that selecting a union would be futile.”

The ULP claim doesn’t provide specific examples of Tesla’s alleged violations, nor when they took place, but, according to the filing:

In the past six months, [Tesla] has interfered with the protected Section 7 rights of [redacted] and those of [redacted] coworkers by intimidating [redacted], creating the impression of surveillance of [redacted] and [redacted] coworkers, engaging in surveillance of [redacted] and [redacted] coworkers’ activities, subjecting [redacted] heightened supervisory scrutiny and interrogating [redacted] concerning [redacted] support for and activities on behalf of the [UAW].

In a statement to Jalopnik, a Tesla spokesperson said the latest claims were part of an “ongoing organizing attempt” by the UAW, and “not surprisingly were nearly identical to their previous claims.”

“To be clear, the NLRB has made no determination on their merits,” the spokesperson said. “We remain focused on our mission to accelerate the world to sustainable energy, and continuing to make Tesla an even better place for our employees to work.”

But the filing doesn’t mean the UAW has an active campaign to unionize the Gigafactory. The UAW told Jalopnik it doesn’t comment on organizing inquiries as a matter of policy, but the complaint suggests that some of the Gigafactory’s roughly 7,000 workers have at least discussed the possibility of unionizing.

Tesla has faced a wave of worker complaints this year about pay, safety and labor rights violations, all the while pushing back against the UAW’s organizing campaign. The UAW has been vocal about wanting to organize the Fremont plant, an idea continually rebuffed by , who has gone so far as to claim he’d work .

After Tesla fired several hundred employees in October, citing “performance” issues, the UAW filed a claim with the NLRB, accusing the company of dismissing employees who openly advocated for unionizing the California factory. , saying they received excellent remarks in their last known performance reviews.

The NLRB, in its August complaint, said it found merit to previous allegations made by Tesla employees about unfair labor practices. Tesla has denied the charges. A hearing was scheduled for mid-November, but to investigate new charges related to the case.