U.N. Secretary-General Ban Ki-moon emerged as the most favored potential presidential candidate for next year's election, a poll showed Thursday, bypassing long-established hopefuls in the opposition parties.

According to the survey conducted by Realmeter on 2,018 South Koreans earlier this week, Ban held an approval rate of 25.3 percent, outpacing other potential candidates. It marked the first time for Ban to be included in the Realmeter survey, which is one of the key barometers to gauge public sentiment.

During his visit to Seoul last month, Ban said he would "contemplate" what he would do as a South Korean citizen when he returns to his home country after completing his two terms as U.N. helmsman at the end of this year. He did not directly deny the speculation that he will run for the presidency. Political watchers said if he opts to run, Ban will probably seek the ruling Saenuri Party's ticket, which can put a dent in the opposition's plans for regime change in 2018.

Moon Jae-in, former leader of the Minjoo Party of Korea, held 22.2 percent, up 0.7 percentage point from a week earlier. Ahn Cheol-soo, co-chairman of the minor People's Party, saw his approval rate drop 3.2 percentage points to 12.9 percent.

Realmeter said if Ban runs for president the race slated for late next year will become a contest between the U.N. chief and Moon. Until Ban hinted at his political ambitions, many here believed the race would pit Moon against Ahn, with any ruling party candidate coming in third.

President Park Geun-hye's approval rating stood at 36.1 percent, up a noticeable 2.2 percentage points from a week earlier.

The disapproval rating edged down 1.6 percentage points over the cited period to reach 59.7 percent.

The ruling Saenuri Party held an approval rating of 30.1 percent, while the main opposition Minjoo Party managed to narrow its gap with its rival by rising 3.4 percentage points to 29.8 percent. The People's Party shed 2.4 percentage points to 17.7 percent. (Yonhap)