South Korean presidential hopefuls hit the road on Saturday as they entered their final campaign stretch with the election scheduled to be held just after three days.

Front-runner Moon Jae-in of the liberal Democratic Party stayed in Seoul and its surrounding cities. He made stops in Incheon and Ansan, before returning to the capital to campaign later in the evening, Yonhap News Agency reported.

Thirteen candidates are vying for the presidential office, with two dropping out earlier in the race.

The second favoured contender Ahn Cheol-soo of the centre-left People's Party, took his campaign to Gwangju, the long-time liberal stronghold in the southwest, and covered populated areas in the metropolitan city some 330 km from Seoul.

The latest poll published on Wednesday showed Moon in the lead with 42.4 per cent, followed by two runners-up — Ahn and Hong Joon-pyo of the former ruling Liberty Korea Party — tied at 18.6 per cent.

The other major candidates included Sim Sang-jeung of the progressive Justice Party, who in the latest poll stood in fourth place with 7.3 per cent, and Yoo Seong-min of the splinter conservative Bareun Party with 4.9 per cent.

In the first early voting for a presidential election held on Thursday and Friday, 11.07 million people, or 26.06 per cent of the electorate, cast their ballots.