The “Gangnam Style” singer Psy has been interrogated by South Korean police in connection with an ongoing sex scandal that has engulfed the K-pop industry.

According to the Hollywood Reporter, Psy was summoned as a reference witness in an ongoing investigation into K-pop mogul Yang Hyun-suk, who has been accused of procuring sex workers for foreign business investors in 2014.

K-Pop stardom luring Japan's youth to Korea Show all 10 1 /10 K-Pop stardom luring Japan's youth to Korea K-Pop stardom luring Japan's youth to Korea Yuuka Hasumi, 17, and Ibuki Ito, 17, from Japan, who want to become K-pop stars, perform at an Acopia School party in Seoul, South Korea. Acopia is a prep school offering young Japanese a shot at K-pop stardom, teaching them the dance moves, the songs and also the language Images Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Miyu Takeuchi, a trainee with the K-pop agency Mystic Entertainment, sings during a training session in Seoul. Takeuchi said it wasn't a difficult decision to leave a 10-year career with a top idol band AKB48 back home in Japan to sign with the K-pop agency Mystic Entertainment in March as a trainee. Even with her experience, she has seven hours of vocal training a day and two-hour dance lessons twice a week, plus early morning Korean lessons. She is not allowed to have a boyfriend but she says she has no regrets, despite the fact there is no guarantee she will make it. "I don't know how long my training period will be, but it has to reach a point where my coaches and management company say 'Miyu, you are a professional!'" Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Yuuka sings a song as she spends time after class, in the Hongdae area of Seoul. She put high school in Japan on hold and flew to South Korea in February to try her chances at becoming a K-pop star, even if that means long hours of vocal and dance training, no privacy, no boyfriend, and even no phone. "It is tough," Hasumi said. "Going through a strict training and taking my skill to a higher level to a perfect stage, I think that's when it is good to make a debut" Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao Niitsu, 19, a college freshman from Tokyo, who wants to be a K-pop star, practices dancing to K-pop songs in her room in Tokyo. "I've heard stories about no free time or not being able to do what I want. But, I think all of K-pop stars who are now performing have gone down the same road," said Niitsu Reuters/Kim Kyung Hoon K-Pop stardom luring Japan's youth to Korea Yuho Wakamatsu, 15, who wants to become a K-pop star, adjusts her makeup during a training session in Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao and other children sit on a bus heading for an audition in Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Yuuka and Ibuki at a street performance in Hongdae area of Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao chooses her profile picture before an audition in Seoul. During a visit to Seoul paid for by her mother, herself a die-hard BTS fan, Niitsu auditioned for 10 agencies and was accepted by five Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea A K-pop applicant performs at an audition in Tokyo Reuters/Kim Kyung Hoon K-Pop stardom luring Japan's youth to Korea Nao and other Japanese children warm up for an audition at a park in Seoul Reuters/Kim Hong-Ji

Yang, the founder of K-pop label YG Entertainment, this week quit his roles within the company (whose clients include Psy, Blackpink and 2NE1) amid an investigation into the label and some of its associated acts.

The scandal began when police charged the musician Seungri, a singer in the YG boyband BIGBANG, with operating a prostitution ring within a popular South Korean nightclub.

The investigation widened from there, with Yang accused of tax evasion, the fostering of a corrupt relationship with South Korean police and the covering up of illegal drug use in the boyband iKON. He is also accused of procuring sex workers for an event set up to woo potential Southeast Asian investors.

Psy, who was also in attendance, has reportedly told police that he was unaware of any illegal activity at the event. The singer and rapper had previously boasted of a friendship with the Malaysian businessman Jho Low, who is currently a fugitive from the law amid the 1MDB money laundering scandal and who was also a guest at the event.

Psy informed the police that he and Yang both left the event early. Yang has denied all allegations against him.