HONG KONG — A leading K-pop singer has been formally named as a suspect in an investigation into accusations of prostitution and sexual misconduct at nightclubs in South Korea.
The police in Seoul, South Korea, said that the singer, Lee Seung-hyun, 28, who performs under the name Seungri and is a member of the boy band Big Bang, was suspected of “offering sexual services” in 2015.
Local news reports, citing what they said were leaked posts from a messaging app, said Mr. Lee was accused of arranging for investors to receive sexual favors at a nightclub called Arena.
Mr. Lee has denied the accusations against him, but said that he would nonetheless retire from the entertainment scene to protect the reputation of his band and of the talent agency that manages it, YG Entertainment.
“I will take the investigation seriously to clear all the allegations,” he wrote in an Instagram post on Monday.
Mr. Lee is not in custody, and YG Entertainment said he would begin his mandatory military service on March 25. The police said they had made arrangements for the investigation to continue after he enlisted.
The investigation appears to have begun after video circulated online that was said to have shown a man being assaulted by employees at another nightclub, Burning Sun, which Mr. Lee has promoted.
According to local media reports, the man said he was attempting to defend a woman who had been molested at the club.
Lee Moon-ho, the head of Burning Sun, was questioned by the police for 10 hours, according to local news reports.
In a statement he posted to Instagram before deleting his personal account, he said that many unfounded rumors were circulating about misconduct at the club — he cited claims of police collusion, drugging and sexual assault of women, and drug sales — but that the alleged assault on the man was the only confirmed episode.
“On the cases related to Burning Sun that I did not know about, I will actively participate in the investigations to ensure that the truth is quickly uncovered and I am making efforts to prevent these issues from arising again,” he wrote.
Prostitution is illegal in South Korea, but businessmen are thought to sometimes arrange illicit sexual encounters in exchange for deals.
As Seungri, Lee Seung-hyun has an outsize presence in Seoul’s night life and music scene, and also has his own chain of ramen restaurants. He has cultivated an image evoking F. Scott Fitzgerald’s Jay Gatsby, with a solo tour and album under the title “The Great Seungri.”
Representatives from Arena declined to comment. Spokesmen for Burning Sun could not be reached for further comment; a representative was quoted in the South Korean daily Kyunghyang Shinmun as saying that Seungri was part of its management, but not its owner.
The chief executive of YG Entertainment said in a statement that Seungri was no longer executive director at the club, and that he would be resigning from his business roles before he enlisted in the military.
The accusations have rocked fans from South Korea and abroad. Some defended the star and lamented his downfall, while more than 200,000 others signed a petition calling for the police to punish him, and to act on other allegations of corruption and drug crimes against women at adult entertainment venues.
“We demand self-reflection among male celebrities who are the perpetrators and abettors of rape culture; who saw women as sexual tools rather than human beings to be respected, actively participated in crime or condoned, assisted or enjoyed it,” Digital Sexual Crime Out, a feminist activist group, said in a statement. “We also demand self-reflection among men who related to these male celebrities and consumed the case as simple gossip.”