South Korean stocks ended 0.77 percent lower on Tuesday as investor sentiment was dented by rising concern over North Korea's nuclear test, analysts said Tuesday. The local currency fell against the U.S. dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) shed 15.03 points to 1,938.18. Trading volume was moderate at 361.3 million shares worth 3.7 trillion won (US$3.4 billion), with decliners far outpacing gainers 602 to 215.

"Rising geopolitical risks stemming from North Korea's pledge to carry out a nuclear test weighed down investor sentiment," said Han Beom-ho, a senior analyst at Shinhan Investment Corp.

Last month, North Korea vowed to conduct its third nuclear test in response to the U.N. Security Council resolution tightening sanctions against it as punishment for its December rocket launch.

South Korea's ambassador to the U.N. said Monday another nuclear test appears imminent, echoing various media reports that the secretive communist nation is technically ready for it, although when the leadership will give the order remains unclear.

Foreigners purchased a net 3.5 billion won worth of local shares, and retail investors also scooped up a net 124.3 billion won. On the other hand, institutional investors dumped a net 131.2 billion won.

Leading exporters fell across the board, with market behemoth Samsung Electronics falling 0.14 percent to 1,435,000 won, and top auto parts manufacturer Hyundai Mobis losing 0.51 percent to 290,000 won.

NHN, the operator of South Korea's most visited Web portal, plunged 4.73 percent to 231,500 won on reports that the firm is considering spinning off its mobile business segment.

Woori Finance Holdings dropped 2.38 percent to 12,300 won due to the weak earnings outlook for the fourth quarter of fiscal 2012.

The firm closes its books on March 31.

In contrast, casino and ski resort operator Kangwon Land soared

3.64 percent to 32,750 won on the firm's plan to expand business facilities.

The local currency closed at 1,087.00 won against the greenback, down 2.40 won from Monday's close, following the political uncertainties in Spain and Italy, dealers said.

Bond prices, which move inversely to yields, closed higher. The yield on three-year Treasuries moved down 0.01 percentage point to

2.75 percent and the return on the benchmark five-year government bonds fell 0.02 percentage point to 2.88 percent. (Yonhap News)