It is the first time Park has mentioned corruption in her public appearances on a nationwide campaign trail to try to win the party's nomination for the December presidential election.

Her comment came four days after Lee apologized to the nation over a string of money-for-influence scandals involving one of his elder brothers and his former aides.

Lee Sang-deuk, a 76-year-old brother of Lee, was indicted earlier this week on charges that he received about 750 million won ($658,000) in bribes from two troubled savings banks and a local company.

Park's comment underscored her thinly-veiled commitment to making a clean break with the president to try to win public support for her candidacy for the nation's top political job.

She has long been a front-runner in opinion polls for the December presidential election. The ruling party is scheduled to select its presidential nominee at a national convention on Aug. 20.

Previous governments were also plagued by corruption cases in their final years in office.

In 2003, then President Roh Moo-hyun vowed to fight against corruption. However, Roh committed suicide in 2009 amid a prosecution investigation into allegations his family members took illicit funds.

Transparency International, an anti-corruption watchdog, ranked South Korea 43rd out of 183 countries in its Corruption Perceptions index in the order of corruption-free countries last year. (Yonhap News)