South Korean stocks continued an upward trend in the first trading session on Thursday after the Lunar New Year holidays.

The benchmark KOSPI jumped 158.60 points, or 2.88 percent, to trade at 5,665.61 as of 11:31 a.m. local time (0231 GMT), surpassing the 5,600 points for the first time.

The smaller KOSDAQ surged 47.26 points, or 4.27 percent, to 1,153.34 during the morning trading.

A buy-side sidecar was issued as the KOSDAQ 150 futures soared over 5 percent.

The sidecar refers to a temporary halt of program trading orders for five minutes that is triggered when the KOSDAQ 150 futures rise or fall by more than 5 percent.

Institutional investors led the KOSPI rally, while the KOSDAQ extended its early gains thanks to purchases by both institutional and foreign investors.

Market bellwether Samsung Electronics and memory chip giant SK Hynix advanced 4.64 percent and 1.99 percent.

The country's top automaker Hyundai Motor added 0.60 percent, and the largest battery maker LG Energy Solution increased 1.52 percent.

The No. 1 biopharmaceutical contract manufacturer Samsung Biologics rose 2.16 percent, and the leading aerospace and defense company Hanwha Aerospace gained 2.99 percent.

The biggest shipbuilder HD Hyundai Heavy Industries picked up 6.08 percent, and the energy infrastructure leader Doosan Enerbility was up 2.48 percent.