"It's been really tough and unfair," she told reporters. "I just hope the truth is revealed."

She's suspected of writing numerous defamatory comments using what police have identified as her Twitter ID, "Hyekyunggung Ms. Kim," before and during elections in recent years.

Most of the comments targeted the governor's political rivals, including President Moon Jae-in, who contended against Lee in the Democratic Party's primary for the 2017 presidential election.

The Twitter ID raised false accusations about Moon's son having landed a job at a public institution because Moon exerted influence while serving as a presidential aide.

Kim has denied any wrongdoing.

Prosecutors raided the governor's properties last week to search for Kim's old mobile phone, which is believed to hold evidence that is crucial to the probe. The phone was never retrieved.

Prosecutors will question her again over alleged involvement in the online slander and other details, including the whereabouts of the missing mobile phone, they said.

Kim is also accused of writing in April this year that one of Lee's rivals in the DP primary for the Gyeonggi Province gubernatorial election collaborated with the conservative opposition Liberty Korea Party.

She faces charges of defamation and spreading of false information.

Lee, former mayor of Seongnam, a city just south of Seoul, has accused the police of making politically motivated, baseless accusations while disregarding any evidence in Kim's favor. (Yonhap)