Exit polls Wednesday indicated South Korea's two top presidential candidates neck and neck in the tightly contested race, with conservative favorite Park Geun-hye holding a slight lead over her liberal rival Moon Jae-in.

Polls jointly conducted by local broadcaster KBS, MBC and SBS put Park at 50.1 percent compared to Moon at 48.9 percent, with a margin of error of 1.6 percent.

A separate survey by broadcaster YTN said Park earned 49.7 percent to 53.5 percent of the vote, while Moon is projected to have gained 46.1 percent to 49.9 percent.

Another exit poll by cable broadcaster JTBC gave 49.6 percent to Park and 49.4 percent to Moon, with the gap well within the margin of error.

Polls opened at 06:00 a.m. local time at 13,542 polling stations nationwide and closed at 06:00 p.m. Definitive results are expected by midnight.

As of 5 p.m., voter turnout was estimated at 70.1 percent, higher than what was reported in the 2007 presidential election that elected Lee Myung-bak, whose single five-year term ends early next year.

Park, the 60-year-old daughter of South Korean dictator Park Chung-hee, is looking to become the first female leader of the country and extend the conservative rule for another five years.

Moon, a 59-year-old former human rights lawyer who was once jailed for protesting the senior Park's authoritarian rule, billed the election as a contest between vested interests and aspirations for new politics.

He is the sole candidate running on the liberal ticket after independent Ahn Cheol-soo and leftist candidate Lee Jung-hee bowed out of the race to throw their support behind him.