Prosecutors on Thursday sought an arrest warrant against a former mayor of South Korea's second-largest city over alleged sexual assault.

The Busan District Prosecutors Office said it has filed a warrant to detain ex-Busan Mayor Oh Keo-don on charges of indecent act by compulsion.

Oh is alleged to have sexually assaulted a city employee at his office in early April. He stepped down from the post on April 23 after apologizing to the victim in a press conference.

The court is expected to hold a hearing on the warrant request as early as Monday.

Oh, who ran as a candidate for the Democratic Party, was elected as the mayor of Busan, 450 kilometers southeast of Seoul, in 2018. The party expelled him in late April.

The mayoral post has been temporarily filled by the city's vice mayor for administrative affairs until a by-election scheduled for April 2021. (Yonhap)