U.N. Secretary-General Ban Ki-moon topped the list of potential presidential candidates in South Korea, data showed Friday, continuing to beat other long-established hopefuls from the opposition parties.

According to the survey conducted by Gallup Korea earlier this week, Ban's approval rate came to 26 percent, followed by Moon Jae-in, former leader of the Minjoo Party of Korea, whose numbers stood at 16 percent, down 2 percentage points from a week earlier.

It marked the first time for Ban to be included in the Gallup poll.

Ahn Cheol-soo, co-chairman of the minor opposition People's Party, saw his approval rate plunge 10 percentage points to 10 percent. The survey was conducted on 1,002 South Koreans.

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.

Gallup Korea said Ban was included on the survey starting this month as his remark can be considered as a political intention.

President Park Geun-hye's approval rating stood at 31 percent, down 3 percentage points from a week earlier. The disapproval rating held steady at 54 percent over the cited period.

The ruling Saenuri Party, meanwhile, held an approval rating of 29 percent, while the main opposition Minjoo Party posted 24 percent, down 3 percentage points on-week. The People's Party shed 4 percentage points to 17 percent. (Yonhap)