The number of overseas voters marked 75.3 percent of 294,633 people who had registered to vote. It also marked a 40.3 percent spike from 158,225 overseas voters who took part in the country's last presidential election held in 2012, the NEC said in a press release.

In addition to the 1.97 million South Koreans staying overseas, there are about 42.4 million eligible voters here.

Earlier Monday, the NEC launched a four-day absentee voting period for those who will not be able to visit polling stations on the election day, including people with disabilities and those who will be aboard ships.

A separate two-day early voting period is also scheduled for Thursday and Friday for any voter who wishes to vote in advance.

All votes cast in advance, including those by overseas voters, will be kept sealed until they are officially counted on election day, the NEC said. (Yonhap)