Federal prosecutors have accused Fiat Chrysler Automobiles NV and the United Auto Workers union of conspiring to violate U.S. labor laws, Reuters reported, citing a court filing.

The U.S. Justice Department said a former executive at the automaker knew that bribes paid to union leaders were designed to facilitate labor negotiations.

The filing, submitted to the U.S. District Court for the Eastern District of Michigan in Detroit on May 25, is related to a guilty plea by former Fiat Chrysler director of employee relations Michael Brown about his knowledge of Fiat executives' alleged bribery of the UAW officials who served on the union's negotiating committee, according to Reuters.

"Michael Brown knew that the purpose of the conspiracy to provide prohibited payments to UAW officials was to grease the skids in order to obtain benefits, advantages and concessions in the negotiation, implementation and administration of the collective bargaining agreements between [Fiat Chrysler] and the UAW," The Detroit News quoted the prosecutors as saying in the federal court filing.

The prosecutors said Fiat Chrysler and the UAW conspired from before 2009 to 2015 to violate the Labor Management Relations Act, which prohibits employers or those working for them from giving money or other valuables to officers or employees of labor organizations and labor leaders from accepting such items, according to The Detroit News, which first reported the filing June 13.

Reuters said the government has secured five other guilty pleas in the continuing investigation.

Outgoing UAW president Dennis Williams said at a conference in Detroit on June 11 that the union's leadership team had no knowledge of the misconduct until the government told them. Fiat Chrysler had no further comment, according to Reuters.