(Bloomberg) -- The United Auto Workers is asking the US labor board to overturn its unionization defeat at Mercedes-Benz Group AG’s Alabama plants last week, alleging that illegal interference by the company prevented a fair vote.

Employees at Mercedes’ facilities in Vance and Woodstock voted 2,642 to 2,045 against unionization last week, a significant setback for the recently reinvigorated union’s efforts to grow its ranks.

In a Friday filing with the US National Labor Relations Board, the UAW urged the agency to hold a new election due to what it called Mercedes’ “wanton lawlessness” leading up to the last one. The union’s filing accuses the company of holding coercive mandatory anti-union meetings, making “inflammatory appeals to racial prejudice,” targeting pro-union employees for drug tests, and terminating four UAW supporters.

Earlier complaints the union filed with the US and German governments accusing Mercedes of illegal union-busting are still pending. The US government also took the unusual step of raising concerns about such allegations with Germany ahead of the vote.

Mercedes has denied wrongdoing. “We sincerely hoped the UAW would respect our Team Members’ decision,” a company spokesperson said in an emailed statement Friday. “Throughout the election, we worked with the NLRB to adhere to its guidelines and we will continue to do so as we work through this process.” 

The company said the election showed the majority of its employees “are not interested in being represented by the UAW.”

The UAW’s new filing sets up what could be a lengthy and contentious legal proceeding, heightening scrutiny on Mercedes’ behavior and influencing how other automakers choose to respond to the union’s organizing efforts. Such filings are considered by regional NLRB officials, who have authority to throw out the results of an election they find was tainted by misconduct, and to order a new vote be held.

“In a fair fight, where Mercedes is held accountable to following the law, workers will win their union,” the UAW said in an emailed statement. “All these workers ever wanted was a fair shot at having a voice on the job and a say in their working conditions. And that’s what we’re asking for here.”

(Updates with information from filing, Mercedes-Benz comment starting in third paragraph.)

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