Lee Sun-kyun, who stars in the Oscar-winning film "Parasite," attends a press conference at a Seoul hotel, in this Feb. 19, 2020 file photo. Yonhap

Police are said to have launched an internal investigation against actor Lee Sun-kyun, best known for his role in the Oscar-winning movie "Parasite," over suspected drug use, according to sources Friday.

The Incheon Metropolitan Police Agency had begun an investigation into eight people, including the actor and a chaebol offspring, over allegations they took illegal drugs multiple times this year.

While the police have not officially named Lee as a suspect, they are said to have discovered a lead in connection with the actor's illegal activities.

"We sincerely apologized for causing concerns over reports about actor Lee Sun-kyun. We are checking the veracity of the suspicions raised against Lee, and will fully cooperate with any future police investigation," HODU&U Entertainment, Lee's agency, said in a press release.

The company said the actor filed a complaint of blackmail with the police against another person involved in the drug case Lee was allegedly associated with.

Lee claimed the person blackmailed him and extorted hundreds of thousands of dollars from him.

Veteran actor Lee, 48, starred in "Helpless" (2012), "All About My Wife" (2012) and "A Hard Day" (2014). He won a Screen Actors Guild Award with his cast mates for his role in "Parasite" by director Bong Joon-ho. (Yonhap)