The prosecutors' office formed an investigation team of four prosecutors.

"We will conduct an investigation in a thorough and speedy manner in accordance with law and principles," an official said. "We will also ensure the safety of the victim."

The victim, Kim Ji-eun, who served as An's political affairs secretary, claimed in a TV interview Monday night that An forced her to have sex with him four times over the past eight months.

An, a popular politician who had been widely considered a potential presidential candidate, has apologized and resigned as governor. His ruling Democratic Party also decided to expel him from the party.

A lawyer for Kim said that she wanted to file the case with the western district prosecutors' office because a sexual assault incident happened in the office's jurisdiction.

An plans to hold a press conference Thursday, an aide said.

An's former chief of staff, Shin Hyung-cheol, said in a mobile text message that An plans to offer words of apology during the conference set to take place at the South Chungcheong Province government building around 3 p.m. It will be An's first public appearance since the allegations were first raised.

Shin also said earlier that An is considering hiring a lawyer.

Another alleged victim also claimed on Wednesday that she was repeatedly sexually harassed several years ago.

In an interview with JTBC, the woman, whose identity has been withheld, said the former governor harassed and attempted to rape her a total of seven times. (Yonhap)