Hyundai Motor's vice chairman has said it would be difficult for the United Auto Workers (UAW) to unionise workers at the automaker's Alabama plant in the United States.

Hyundai factory workers do not see the need to join the UAW union because Hyundai gives them stable jobs, said Yoon Yeo-cheol, who is in charge of Hyundai's labour relations.

"It will not be easy (for the UAW to unionise Hyundai workers). Hyundai employees there don't like it," he told Reuters in Seoul.

UAW president Bob King has said he wants to target a Japanese, South Korean or German automaker with US plants in its campaign to unionise workers at plants of non-US automakers.

The UAW protested at about 75 US Hyundai dealerships last week in support of a South Korean woman who filed a sexual harassment claim against one of the automaker's suppliers.