DETROIT - Workers at a Ford Motor Co assembly plant in Missouri have started a vote that would authorize a strike as the automaker and the United Auto Workers union continue talks aimed at resolving disputes over local plant conditions.

About 3,500 hourly workers at Ford's Kansas City, Missouri plant began voting on Thursday and are scheduled to conclude the process on Saturday, Ford spokeswoman Marcey Evans said.

The strike authorization vote -- if passed -- would give the UAW the ability to call a strike at a plant that assembles F-150 pickup trucks and the Ford Escape and Mercury Mariner crossovers.

Evans said that it has been more than 20 years since a strike authorization vote has led to a work stoppage.

The vote at UAW Local 249 comes less than two weeks after Ford's 41,000 U.S. factory workers overwhelmingly rejected a proposed cost-cutting deal that would have brought its labor costs in line with General Motors Co and Chrysler.

Opposition to the proposed concessions was particularly fierce at the Kansas City plant, with 92 percent voting against the deal. The national average was 70 percent for production workers and 75 percent for skilled trade workers.

The union local has raised concerns regarding working conditions, workload and job security.

UAW Local 249 President Jeff Wright said on the local union's Web site that disciplinary actions have piled up and working conditions have become intolerable.

Wright added that UAW Vice President Bob King, who heads the union's negotiations with Ford, said the UAW leadership would also stand behind the local in the work standards fight even if it meant going on strike.

Wright was not immediately reached for comment on Thursday.

Evans said that Ford's executives, local union leaders and national UAW preventatives are in talks to address the concerns raised by the workers.

UAW President Ron Gettelfinger told Reuters last week that Ford's relative health compared to GM and Chrysler was a factor in the recent rejection of the additional concessions.

Ford posted a nearly $1 billion profit in the third quarter and $1.3 billion of positive cash flow from its auto business.

In February, unionized workers at Ford agreed to major concessions to change the 2007 contract that allowed Ford to convert half of its retiree healthcare obligations to stock, from cash.

(Reporting by Soyoung Kim)