Moon Jae-in, a front-runner presidential candidate from the liberal bloc, stood as the top contender in a local opinion poll, despite former UN Secretary-General Ban Ki-moon's efforts to expand his presence after returning home.

According to the data compiled by RealMeter last week, Moon held an approval rating of 29.1 percent, approaching the 30 percent level. The study was conducted on 2,520 South Koreans with a margin of error of plus or minus 2 percentage points.

The pollster said the figure set a new record by beating the 27.9 percent posted in April 2015. The support rating for Ban, the most favored candidate from the conservative bloc, on the other hand, fell 2.4 percentage points on-week to 19.8 percent.

For Ban, it marked the first time his numbers fell below 20 percent since early December.

Seongnam Mayor Lee Jae-myung posted 10.2 percent, with his figure falling for the second consecutive month. South Chungcheong Gov. Ahn Hee-jung followed with 4.7 percent. 

Acting President and Prime Minister Hwang Kyo-ahn, who was included in the poll for the first time, held an approval rating of 4.6 percent.

By party, the main opposition Democratic Party posted an approval rating of 38 percent, trailed by the ruling Saenuri Party with 12.5 percent. The People's Party posted 11.5 percent, while the conservative bloc's splinter Bareun Party held a comparable figure of 8.9 percent. (Yonhap)