FNC Music, the agency of band CNBLUE, issued an apology for the assault of a teenage fan by the group's manager.
The apology came hours after a video clip showing the manager beating a female student in the head with his hand several times surfaced on the Internet on Sunday.
FNC Music posted the apology on its Web site, Sunday, after a slew of comments critical of the assault were posted online.
The agency said the incident occurred in a KBS TV parking lot on Feb. 11, while the group members were blocked by their fans as they attempted to enter the broadcaster's building.
The manager "acted violently" when a fan pulled the hood of group member Lee Jong-hyun, nearly causing him to fall, the statement said.
It said the manager became violent due to frustration over their repeated failure to make way through the throng of fans.
"The manager and the entire staff of FNC Music are very sorry for the incident as we know that violence should not be used under any circumstances," it said.
It also pledged the agency will work with the manager to stem the recurrence of a similar incident.
The band has been at the center of a dispute after its hit song "I'm a Loner" was accused of having plagiarized indie band Ynot's song "Blue Bird." The songwriter has denied the allegation.
CNBLUE is comprised of guitarist and lead singer Jung Yong-hwa, guitarist and vocalist Lee Jong-hyun, drummer Kang Min-hyuk and bass guitarist Lee Jung-shin.

소년 밴드 씨엔 블루 기획사인 FNC 음악이 이 그룹의 매니저가 10대 팬의 폭행에 대해 사과했다.
이 사과는 손으로 여러 차례 여학생을 때리는 확인 미상의 매니저가 보이는 동영상이 일요일 인터넷에 떠돌자 수시간만에 나왔다.
폭행에 대한 수많은 비난 댓글이 웹사이트에 올라왔다.
FMC 음악은 일요일 자체 웹사이트에 사과문을 게시했다. 게시문에서 2월 11일 KBS 주차장에서 일어났다며 그룹 멤버들이 KBS에 들어가려는데 팬들이 막자 사건은 밝혔다.
성명서는 매니저는 팬이 넘어질 정도로 과격하게 멤버인 이종현의 후드를 잡아당기자 "폭력적으로 행동했다"고 밝혔다.