Police have sent prosecutors papers on four South Korean men, requesting their indictment for allegedly spitting on a statue of a girl symbolizing victims of Japan's wartime sex slavery, investigative sources said Monday.

According to the police, the four men in their 20s and 30s spat and shook their hips in front of the statue in a public square in Ansan, southwest of Seoul, at around midnight on July 6.

The installation is one of several statues erected across the country to commemorate South Korean women known euphemistically as "comfort women" who were forced into sexual slavery by the Imperial Japanese Army during World War II while the Korean Peninsula was under Japan's colonial control.

The four, booked without detention, have been quoted as saying they intended to "ridicule the comfort women victims" when they spat on the statue. CCTV footage showed that they also shouted in Japanese, "Long live the (Japanese) emperor." During an interrogation, they said, "Speaking Japanese seemed to be more insulting to comfort women victims," according to police.

The House of Sharing, a shelter for comfort women victims in Gyeonggi Province near Seoul, filed an official compliant with the police on behalf of six surviving sex slavery victims, bracing itself against the possibility that the accused men will refuse to apologize.

The six women earlier said they would not raise a formal charge on condition that the men officially apologize, partly blaming society for their distorted view of history.

One of the four men, along with his father, visited the house and offered them an apology, an official at the shelter said, adding that the other three plan to follow suit this week.

The surviving sexual slavery victims will withdraw the complaint the house filed if the men offer an official apology, the official said. If the victims withdraw the complaint before the first of the men's trials, the four are expected to evade punishment because a defamation case requires an official complaint by the victim.

The statue was erected in the city on Aug. 15, 2016, to mark the 71st anniversary of Korea's liberation from Japanese colonial rule. Citizens launched a street campaign and used crowd funding to help raise money to erect the statue. (Yonhap)