Millions vote for a new president, after six months of turmoil sparked by a failed martial law attempt and the impeachment of former leader Yoon Suk Yeol.

Pre-election surveys suggest Yoon Suk Yeol's liberal rival, Lee Jae-myung, appears headed for an easy win, riding a wave of public frustration in the wake of Yoon's martial law debacle.

A closer race than many first thought is now expected between the opposition front runner and the conservative ruling party candidate.