A college professor was questioned for the second day Saturday on suspicion that he had dropped out of last year's election for Seoul's education chief in exchange for money, prosecutors said.

Park Myoung-gee, a professor at Seoul National University of Education, was taken into custody Friday over allegations that he had received 130 million won ($120,147) from then rival and now education chief Kwak No-hyun.

Park is alleged to have received the money through his brother, also under custody, from a confidant of the education chief on three occasions between February and April this year.

Prosecutors suspect that the money might have been a reward for the professor's withdrawal from the election. He pulled out of the race about two weeks before the vote, saying that unity was needed to confront a powerful pro-government candidate.

Park's withdrawal was believed to have been a key factor in Kwak's victory in the election.

Prosecutors also suspect that Park's recent appointment as a member of an advisory council for the Seoul Metropolitan Office of Education could also have been a reward for his withdrawal from the election.

Kwak, a liberal-leaning education reformer, has clashed with former Seoul Mayor Oh Se-hoon and his conservative ruling Grand National Party over a series of policies, including the controversial decision to give free lunch to all schoolchildren.

The professor's detention came days after an attempt to block the free lunch program fell through as a referendum on it failed to draw enough voters on Wednesday. On Friday, Oh resigned as mayor as he had pledged to quit unless the free lunch program is stopped through the vote.

Oh has denounced the program as populism and called for free lunch only for needy students.

Opposition parties denounced the prosecution's move, calling it a retaliation against the liberal Kwak who has often stood up against the conservative government of President Lee Myung-bak. (Yonhap)