South Korean stocks slumped for the third consecutive session Tuesday amid uncertainties related to the longer-term US Treasury yields and US-China political ties. The Korean won fell against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 30.72 points, or 1.01 percent, to close at 3,004.74 points.

Trading volume was moderate at about 1.3 billion shares worth some 15.9 trillion won ($14.1 billion), with gainers outnumbering losers 653 to 216.

Foreigners sold a net 478 billion won, extending their selling streak to a third session, while retail investors purchased a net 1 trillion won. Institutions offloaded a net 541 billion won.

The KOSPI got off to a strong start on overnight tech gains on Wall Street, briefly touching the 3,058.79-point ceiling, as the 10-year US Treasury yields subsided below 1.7 percent.

But the stock index turned lower to losses late morning, tracking losses on the Chinese stock indices.

Stocks deepened losses following the news reports that the US, Canada, European Union and Britain launched sanctions against officials in China in protest of the communist state's alleged abuses in Xinjiang, western China.

"Investor wariness increased against China's potential retaliation against the Xinjiang-Uyghur human rights sanctions by the US and other European countries," Shinhan Investment analyst Choi Yoo-joon said.

Most large caps closed lower in Seoul.

Top cap Samsung Electronics slipped 0.24 percent to 81,800 won, and No. 2 chipmaker SK hynix shed 2.17 percent to 135,000 won.

Leading chemical firm LG Chem retreated 3.73 percent to 775,000 won, and rechargeable battery maker Samsung SDI moved down 2.8 percent to 624,000 won. Top automaker Hyundai Motor declined 1.09 percent to 226,500 won.

Giant pharmaceutical firm Samsung Biologics edged down 0.28 percent to 713,000 won, but Celltrion gained 1.21 percent to 292,500 won.

Top internet portal operator Naver dropped 2.65 percent to 386,000 won.

The local currency closed at 1,129.7 won against the US dollar, down 1.3 won from the previous session's close.

Bond prices, which move inversely to yields, closed mixed. The yield on three-year Treasurys added 0.2 basis point to 1.132 percent, while the return on the benchmark five-year government bond lost 2.9 basis points to 1.586 percent. (Yonhap)