South Korean stocks plunged nearly 2 percent Monday morning amid spreading virus concern. The Korean won steeply fell against the US dollar.

The benchmark Korea Composite Stock Price Index (Kospi) retreated 54.73 points, or 1.81 percent, to close at 2,963 points, the lowest closing since Dec. 2.

Trading volume was low at about 371 million shares worth some 8.5 trillion won ($7.1 billion), with losers outnumbering gainers 785 to 117.

Foreigners offloaded a net 552 billion won, and institutions dumped 575 billion won, while retail investors scooped up 1.1 trillion won.

After a weak start, the KOSPI increasingly extended its losses in tandem with plunges in the Asian markets.

Concerns about the highly contagious omicron variant of the new coronavirus worsened investor sentiment in South Korea, Japan, China and other Asian regions.

South Korea reported fewer than 6,000 new coronavirus cases for the first time in six days Monday due partly to less testing over the weekend, but the number of new critically ill patients was at almost 1,000. The country has toughened social distancing measures, starting last weekend.

"The impact of the omicron variant seems to have increased (today), compared to the beginning of this month," said Shinhan Investment analyst Choi Yoo-joon.

"Investors seem to be worried over the omicron variant, which might hamper the economic recovery," he added.

Most large caps closed lower in Seoul.

Top cap Samsung Electronics shed 1.15 percent to 77,100 won, and No. 2 chipmaker SK hynix decreased 1.23 percent to 120,500 won.

Internet portal operator Naver retreated 2.99 percent to 373,000 won, leading chemical firm LG Chem tumbled 5.88 percent to 656,000 won, and top automaker Hyundai Motor lost 2.15 percent to 205,000 won.

Among gainers, bio firm SK Bioscience added 1.48 percent to 274,000 won.

The local currency closed at 1,190.8 won against the US dollar, down 9.9 won from the previous session's close. (Yonhap)