With a second round of talks between the United States and Iran again at a turning point after the weekend, South Korea's KOSPI on April 20 edged higher and held above the 6,200 level.

The KOSPI ended the session up 27.17 points, or 0.44 percent, at 6,219.09. It opened up 22.00 points, or 0.36 percent, at 6,213.92 and briefly turned lower before returning to gains.

By investor type, institutions net bought 181.3 billion won. Retail investors and foreigners net sold 277.5 billion won and 159.5 billion won, respectively.

Top market-cap stocks were mixed. Samsung Electronics closed down 0.69 percent at 214,500 won, while SK Hynix finished up 3.37 percent at 1,166,000 won.

LG Energy Solution gained 2.63 percent, SK Square rose 2.79 percent, Doosan Enerbility added 2.30 percent, Samsung Biologics climbed 0.25 percent and Hanwha Aerospace rose 0.14 percent.

Hyundai Motor fell 2.04 percent and Kia lost 1.13 percent.

The KOSDAQ closed up 4.81 points, or 0.41 percent, at 1,174.85. It extended its winning streak to 7 consecutive sessions since April 10.

The won-dollar exchange rate ended the session at 1,476.20 won per dollar, up 8.40 won from the previous session.