South Korean stocks fell to nearly a one-month low on Thursday as the U.S. Federal Reserve struck a cautious note on the global economy amid rising risks of Britain's exit from the European Union. The Korean won firmed against the U.S. dollar.

The benchmark Korea Composite Stock Price Index lost 16.84 points, or 0.86 percent, to close at 1,951.99, booking a sixth straight losing session. Trade volume was moderate at 432.98 million shares worth 4.38 trillion won ($3.74 billion), with losers overwhelming winners 677 to 148.

The U.S. Federal Reserve kept interest rates unchanged on Wednesday in a widely expected move, with Fed Chair Janet Yellen acknowledging Britain's possible exit from the European Union as one of the factors for the latest decision.

The news that Tokyo's Nikkei dropped 3 percent following the Bank of Japan's meeting further pushed down the KOSPI in the afternoon, but foreigners turned to net buyers to pare some of losses.

"Investors are fleeing cyclical stocks and running toward safe havens in the short term due to uncertainties surrounding Britain's June 23 referendum and the global economic slowdown," Kim Jung-hwan, an analyst at Mirae Asset Daewoo Securities, said. "The market will drift without direction for a while as investors are taking wait-and-see strategies ahead of major economic events."

Institutions were the biggest sellers of the day, dumping a net 208.27 billion won. Foreigners bought a net 43.96 billion won, and retail investors picked up a net 115.2 billion won.

Most market heavyweights were in negative terrain.

Top market cap Samsung Electronics declined 0.28 percent to 1,409,000 won, and leading automaker Hyundai Motor slipped 0.74 percent to 134,500 won.

Korea Electric Power Corp., the state-run power provider, rose 0.69 percent to 58,200 won, and AmorePacific, the nation's largest cosmetic maker, gained 0.98 percent to 413,000 won.

Daewoo Shipbuilding & Marine Engineering, the world's second-largest shipbuilder, tumbled 7.19 percent to 4,065 won after the state auditor said Wednesday it had uncovered a combined 1.5 trillion won accounting hole for the fiscal 2013 and 2014 years.

The local currency closed at 1,171.4 won against the U.S. dollar, up 1.9 won from the previous session's close. (Yonhap)