SEOUL, June 30 -- BigHit Music, the agency behind rising K-pop boy group Cortis, has announced an aggressive legal response after discovering that obsessive fans had secretly attached a GPS tracking device to the group's vehicle during a recent schedule in Paris. The agency has vowed to pursue "thorough investigations and severe punishment under a zero-tolerance policy" .

The disturbing revelation was made public on June 29 through a formal notice on the fan platform Weverse, detailing a series of escalating privacy violations against the five-member group, which debuted last August .

According to BigHit Music's statement, the most serious incident occurred during Cortis's recent schedule in Paris. The agency confirmed that several fans...