Main opposition Democratic Party(DP) leader Lee Jae-myung remained tight-lipped when asked about responding to the prosecution's latest summons for questioning over his alleged role in the Daejang-dong development scandal.

Speaking at a forum on online platform regulation and fair trade held at the National Assembly on Tuesday, Lee kept his comments on topic, encouraging respect for innovation while denouncing the damage imposed on others or the market through a monopoly.

Highlighting the government's role in maintaining market fairness, the opposition chief called for the institutionalization of the online platform market to maximize efficiency and public and consumer convenience while ensuring fairness.

Earlier, prosecutors delivered a summons for Lee to appear on January 27 on charges of dereliction of duty and violating anti-corruption law.

Prosecutors suspect that Lee, while serving as the mayor of the Gyeonggi provincial city of Seongnam, helped private investors reap 440 billion won in profits from development projects, incurring losses for the city government.

They suspect that Lee facilitated the receipt of 42-point-eight billion won by his aides, including then-chief policy adviser Jeong Jin-sang, and intervened in drawing election campaign funds in return for business favors.