Kihyun, a member of K-pop boy band Monsta X, on Friday voiced regret and apologized over his "immature behavior" after he was accused of school bullying.

"If there are people who were hurt by my immature attitude and behavior during school, I would now like to sincerely apologize," the singer said in a statement posted on a fan community. "I'm very sorry for disappointing (you) and I will live on deeply reflecting on it."

Kihyun mentioned some episodes from back when he was in middle school but did not directly clarify the school bullying accusations.

"It has been a time for me to doubt myself hundreds and thousands of times whether there are pieces of me that I don't remember since a long time has passed," he said. "When I look back, I was not a loyal student and it's true that I acted in a way that a student should not."

Amid a spate of school bullying accusations that has engulfed the local entertainment industry, some had claimed that Kihyun threatened other students for money or asked them to buy cigarettes for him.

Starship Entertainment, the band's agency, said it is "aware of the seriousness of the issue and believes that it should do its best in fact finding." The agency on Friday shared another statement on the act's fan community, where it said it has "secured testimonies from most alumni that Kihyun was not involved in school bullying."

The company said it has made legal consultations over those who distributed similar accusations in the past, adding it plans to officially file complaints with the police for defamation.

Following a school bullying scandal that erupted with volleyball superstar twins Lee Jae-yeong and Lee Da-yeong, the issue has spread to accusations involving a number of stars in the sports, acting and music industries. (Yonhap)