(Adds details on bargaining talks and background)
By Bernie Woodall and Daniel Wiessner
April 27 (Reuters) - The U.S. National Labor Relations Board on Tuesday filed an unfair labor practices complaint against Volkswagen AG for not bargaining with a portion of plant workers at its Tennessee plant represented by the United Auto Workers union.
Under board procedure, employers must formally refuse to recognize a union certified by the NLRB in order to bring the case to U.S. appeals courts. As the board earlier this month said Volkswagen workers could join the UAW, the agency will likely soon rule against Volkswagen, allowing the company to appeal.
On Monday, Volkswagen said it planned to take the matter, eventually, to a U.S. appeals court.
Last Friday, VW told the UAW that it would not bargain with about 160 skilled trades workers who voted 71 percent in December to be represented by the union. The plant in Chattanooga has about 1,500 hourly workers.
VW said in a statement on Monday that it "will continue our effort to allow everyone to vote as one group on the matter of union representation."
While the skilled trades workers who maintain plant machinery are a fraction of the hourly workforce, VW bargaining with them could serve as a launching pad for the union's efforts to organize other foreign-owned plants in the South. In decades of trying, the UAW has not organized a foreign-owned auto assembly plant in the region.
Volkswagen was at one time welcoming to the UAW at Chattanooga. But that was before the UAW lost a closely contested election open to all of the plant's 1,500 workers in February 2014.
The UAW worked closely with the German union IG Metall in fostering a good relationship with VW before that vote. IG Metall has much more power within VW than the UAW has at any major automaker.
The UAW claims to have majority support from the 1,500 workers at the VW plant, but its executives are fearful that well-financed antiunion lobbying groups will make winning an election difficult.
The UAW is banking on legal precedent that allows a small unit of a worksite to be represented by a U.S. union. (Reporting by Bernie Woodall in Detroit and Daniel Wiessner in Albany, New York; Editing by Bernard Orr)