Former Prime Minister Lee Wan-koo expressed regret Friday over the prosecution's decision to indict him on bribery charges.

On Thursday, prosecutors said they have decided to indict Lee on charges of taking 30 million won ($27,000) from Sung Wan-jong, the former chairman of a construction firm who committed suicide last month, when he was running for a parliamentary seat in April 2013.

Prosecutors, however, failed to clarify when they will indict Lee.

"It is regrettable that the prosecution has decided to indict me even if it is not true that I took illegal political funds from Sung," Lee said in a press release. "I believe I will be exonerated at a court hearing."

A corruption scandal flared up last month after Sung left a note and a recorded interview claiming that he gave money to eight politicians, including Lee and Hong Joon-pyo, governor of South Gyeongsang Province, as well as President Park Geun-hye's former and current chiefs of staff.

Amid the growing scandal, Lee stepped down in April.

The prosecution also alleges that Hong took illegal political funds worth 100 million won from Sung in June 2011. (Yonhap)