Ruling party presidential candidate Lee Jae-myung said Wednesday he is open to an independent counsel investigation into a massive corruption scandal implicating one of his former aides.

Lee of the ruling Democratic Party has previously rejected the main opposition People Power Party's calls for a special counsel probe into allegations that the former aide colluded with a private investor to reap astronomical profits from an apartment development project undertaken in Seongnam, south of Seoul, in 2015, when Lee was the city's mayor.

"I believe we need to see the prosecution's investigation first because it is being done by a state organization," the former governor of Gyeonggi Province said during a forum organized by the Kwanhun Club, an association of senior journalists.

"But if it leaves any loose ends or questions, it will require a more perfect and thorough determination of the truth and strict demands of accountability, be it through a special counsel or in whatever form, and on that point, I fully agree," he said.

The PPP believes Lee was behind the corrupt scheme that awarded a little known asset management company 1,000 times the amount it invested in the development project and accused the prosecution of dragging its feet for political reasons.

Lee has denied involvement in the actual scandal and apologized only for appointing some "polluted" people during his time as mayor.

"I believe that corruption should be handled strictly and have practiced that point myself for a long time," he said.

Lee also accused his opponent and PPP presidential candidate Yoon Seok-youl of turning a blind eye to some of the alleged illegal transactions that occurred during the course of the development project while previously serving as a lead investigator for the case.

"This should also be subject to an investigation, and if that's not enough, it too should be investigated by a special probe," he said. (Yonhap)