SEOUL, Jan. 12 (Xinhua) — Former United Nations chief Ban Ki-moon, who is scheduled to return to South Korea, his home country, later Thursday, has kept his second place in presidential polls for two weeks, a survey showed.

Support for Ban, whose second, five-year term as the UN head ended late last year, was 20.3 percent this week, according to a poll of 1,511 voters conducted by local pollster Realmeter between Monday and Wednesday.

The approval scores of Ban, who is slated to arrive at an international airport in the western port city of Incheon at about 5 p.m. local time, was down 1.2 percentage points from the previous week, staying in the second place for two weeks behind the opposition bloc's powerful contender.

Moon Jae-in, former head of the biggest opposition Minjoo Party, posted 27.9 percent in approval rating, keeping the top rank for the second consecutive week. His rating was up 1.1 percentage points from a week ago.

Meanwhile, Seongnam Mayor Lee Jae-myung of the Minjoo Party saw his approval scores decline 0.7 percentage points to 11.3 percent, maintaining the third place.

Support scores for Ahn Cheol-soo of the minor opposition People's Party rose 0.6 percentage point over the week to 7.1 percent this week, ending a downward trend.