South Korean shares got off to a strong start Wednesday, buoyed by positive investor sentiment from the conclusion of a historic deal on Iran's nuclear program, analysts said.

The benchmark Korea Composite Stock Price Index gained 14.44 points, or 0.7 percent, to 2,073.67 in the first 15 minutes of trading.

Construction shares rallied on rising hope that local builders could clinch large-scale construction deals in Iran once the Middle Eastern country expands infrastructure investment.

Hyundai Engineering & Construction jumped 6.52 percent, and Daelim soared 7.59 percent.

Petrochemicals were up as oil prices, which had remained lower on concerns a deal between Iran and six global powers would result in more supply, edged up after Tuesday's landmark agreement on speculation that sanctions on Tehran's crude exports would not be removed immediately.

Top refiner SK Innovation gained 2.34 percent, and No. 3 S-Oil advanced 1.61 percent.

The local currency was trading at 1,140.6 won against the dollar in Seoul as of 9:15 a.m., up 2 won from Tuesday's close. (Yonhap)