NASHVILLE (AP) - The National Labor Relations Board on Wednesday filed an unfair labor relations complaint against Volkswagen for the German automaker's refusal to bargain with the United Auto Workers union at its lone U.S. assembly plant in Tennessee.

The UAW was elected to represent workers specializing in the maintenance and repair of robots and machinery at the Chattanooga factory on a 108-44 vote in December. But Volkswagen declined to engage in contract talks with the UAW while challenging an NLRB decision to allow the small group of workers to vote on unionization.

The federal labor panel earlier this month rejected Volkswagen's challenge in a 2-1 ruling that found skilled-trades workers "share a community of interest" in terms of qualifications, training, supervision and hours that is distinct from that of the remaining 1,400 hourly production workers in the assembly, body weld and paint shops.

Volkswagen on Wednesday reiterat ed its intention to appeal in federal court because the NRLB panel "declined to fully evaluate" its argument that labor decisions should only be made by the hourly workforce at the plant.

The UAW responded by calling on the federal labor panel to issue an unfair labor practice complaint against Volkswagen.

The dispute comes amid Volkswagen's ongoing efforts to cope with the fallout from its diesel emissions cheating scandal that the company said would cost it $18 billion for 2015 alone. A federal judge last week said VW had agreed with the government to buy back as many as 482,000 diesel cars, as well as pay to make up for the cars' pollution.

The NLRB's decision to reject Volkswagen's challenge of the vote draws on a landmark 2011 NLRB decision in favor of certified nursing assistants at Specialty Healthcare and Rehabilitation Center of Mobile, Alabama. The 2011 decision paved the way for the formation of more of what labor opponents deride as "micro units. "

In that case, the nurses sought to create a 53-person bargaining unit represented by the United Steelworkers at the exclusion of other workers at the nursing home. The NLRB ruling in favor of the nurses was upheld in 2013 by the 6th Circuit U.S. Court of Appeals, which has Tennessee in its jurisdiction.

Volkswagen Group of America, which is based in Herndon, Virginia, hasn't said where it will file its appeal.

Republican politicians in Tennessee and across the region have long spoken out against the United Auto Workers gaining a foothold among foreign-owned plants. And before a 2014 union vote at the plant, Republicans in the state Legislature warned that state grants and incentives could be lost if the UAW won.

The union blamed its 712-626 defeat on unfounded fears sown by labor opponents before the election.