Presidential candidate Yoon Suk-yeol spent much of his allotted time during a debate program Friday on questioning his main rival Lee Jae-myung on allegations of corruption.

Yoon asked Lee during his turn to ask the two other candidates in the debate if Lee would call his past behavior, in which he allegedly favored certain entities in real estate contracts, as truly fair.

The candidate representing the main opposition People Power Party was referring to an allegation that Lee unlawfully favored Doosan Engineering & Construction in 2015 by granting a land area owned by the construction firm to change its purpose to build commercial facilities.

Doosan is suspected of returning the favor by donating 4.2 billion won ($3.5 million) to Seongnam FC, a South Korean professional soccer club based in Seongnam, Gyeonggi Province, while Lee served as mayor for the city.

The club is owned by the Seongnam city government.

Yoon also grilled Lee over the allegation he gave a similar favor to a private developer in regards to land in Baekhyeon-dong, Seongnam. The developer earned an “astronomical amount of profit” from the deal, Yoon claimed.

In asking Lee about the two allegations, Yoon spent most of the time allocated for him to engage in a freestyle debate with two candidates, giving less than a minute to Ahn Cheol-soo, presidential nominee for the minor opposition People’s Party.

Lee flatly denied the allegations Yoon raised against him, saying he should instead be lauded for bringing economic success to the city of Seongnam while he served as Mayor.

He said allegations against him for the case with Doosan and Seongnam FC have already been investigated by the police, saying no charges were brought against him.