UPDATE 1- GM's S.Korea sales slump after shuttering factory

* GM Korea's Feb domestic sales fell 48 pct yr/yr

* GM Korea's estimated 2017 operating loss 800 bln won -regulator (Adds sales breakdown, background)

SEOUL, March 2 (Reuters) - General Motors' sales in South Korea slumped 19 percent in February, hurt by its decision to shut down one of its factories in the country.

The U.S. automaker has also said it will decide the fate of its three remaining plants in South Korea in the coming weeks, as it attempts a politically contentious restructuring of its loss-making unit.

GM Korea posted sales of 36,725 vehicles in February. Its domestic sales fell 48 percent to 5,804, while its overseas exports dropped 9 percent.

A GM Korea dealer in Seoul said the planned shutdown has hurt the image of the company, and customers are concerned about services and residual values.

GM Korea trails far behind South Korea's top automaker Hyundai Motor and second-ranked Kia Motors , with a market share of 7 percent versus the combined market share of 68 percent of Hyundai/Kia, according to government data.

GM Korea likely made an operating loss of 800 billion won ($740 million) last year, the fourth consecutive year of losses after being hit by GM's withdrawal of the Chevy brand from Europe in 2013, South Korea's financial regulator said this week.

($1 = 1,080.4500 won) (Reporting by Joyce Lee and Hyunjoo Jin Editing by Edwina Gibbs)