UPDATE 1-Nissan Mississippi workers vote heavily against unionization

(Adds background, details, company comment, union allegations)

CINCINNATI, Aug 5 (Reuters) - Workers at Nissan Motor Co Ltd's plant in Canton, Mississippi, voted heavily against union representation, the company and the United Auto Workers (UAW) said late on Friday.

The vote extended a decades-long record of failure by the union to organize a major automaker's plant in the U.S. South.

The UAW had put 10 years of groundwork into the vote at the Japanese automaker's Mississippi facility, after two unsuccessful attempts at a Nissan plant in Tennessee, only to fall well short in a bitterly contested campaign that the union maintained was a continuation of the civil rights struggle of the 1960s.

Nissan said the tally of votes, which was overseen by the U.S. National Labor Relations Board (NLRB), was 2,244 votes against unionization to 1,307 in favor.

"With this vote, the voice of Nissan employees has been heard," Nissan said in a statement. "They have rejected the UAW and chosen to self-represent, continuing the direct relationship they enjoy with the company."

The UAW has maintained that Nissan has illegally threatened workers with the closure of their plant or the loss of their jobs if they voted in favor of unionization, a claim Nissan hotly denies. That claim has been backed by a number of complaints lodged by the NLRB.

The union said in a statement it is asking the NLRB to proceed with a trial to "stop Nissans serial commission of unfair labor practices in Mississippi."

"The result of the election was a setback for these workers, the UAW and working Americans everywhere, but in no way should it be considered a defeat," UAW president Dennis Williams said in a statement. (Reporting by Nick Carey; Editing by Paul Tait)