Main opposition Democratic Party of Korea Chairman Lee Jae-myung, left, speaks at a party Supreme Council meeting in Incheon, west of Seoul, Jan. 11. Yonhap

Opposition leader Lee Jae-myung on Wednesday renewed his pledge not to give way against what he called the prosecution's "violent attempt to distort and fabricate," a day after he was questioned over bribery allegations.

In a questioning that lasted roughly 12 hours, Lee, chairman of the main opposition Democratic Party of Korea (DPK), was grilled by prosecutors on Tuesday over allegations that the city government of Seongnam attracted 17 billion won ($13.7 million) in corporate donations to its municipal football club in return for administrative favors when he was mayor.

Lee has denied any wrongdoing, claiming that the advertisements would only benefit citizens of Seongnam, south of Seoul, by reducing taxes. He said the probe is a politically motivated attempt to remove him and suppress the main opposition party.

"Standing up against the political prosecution, I responded to the questioning with my head held high," Lee said in his party's Supreme Council meeting held in Incheon, west of Seoul.