The U.S. government has been in communication with Germany about alleged union busting activities by Mercedes-Benz in Alabama, according to Bloomberg.

At the same time, the European Commission, which represents the European Union in international affairs, has also spoken to the company about its activities in Alabama.

The news comes a week ahead of a high stakes vote on whether the more than 6,000 employees at the German automaker’s Tuscaloosa County plant will be represented by the United Auto Workers.

Bloomberg is citing an unnamed U.S. government official familiar with the discussions with Germany, who said the two governments spoke about allegations that Mercedes fired union activists and held mandatory anti-union meetings.

Last month, the union filed charges under Germany’s Act on Corporate Due Diligence Obligations in Supply Chains, alleging Mercedes-Benz had violated the law. It mandates that companies prevent forced labor and human trafficking, slavery and similar practices in their supply chains, but also forbids non-compliance with labor protections, as well as discrimination and withholding of wages.

A European Commission spokesman said the organization had told Mercedes that “we expect them to respect both local law and European values.”

Mercedes acknowledged speaking with “various authorities,” saying it respects the right of employees to unionize and will “ensure they have the chance to make an informed choice,” Bloomberg reported.

The National Labor Relations Board will conduct voting at the Tuscaloosa County plant May 13 and 17 on whether workers at Mercedes-Benz U.S. International will join the United Auto Workers union. Vote totals are expected May 17.