Actor Yoo Ah-in left police grounds on Wednesday around 6:30 a.m. after 21 hours of questioning over illegal drug use charges.

Yoo, whose real name is Uhm Hong-sik, arrived at Seoul Mapo Police Station around 9 a.m. Tuesday and entered the station without speaking to reporters outside.

He was summoned for questioning over the illegal use of five different drugs, including propofol and cannabis. He was asked how he purchased illicit drugs, how often he consumed them, and whether he had any accomplices.

Yoo did not share the details of what he told the police with reporters Wednesday morning when he left the station.

"I said what I could. I am sorry for causing concerns," he said.

He didn't say whether he admitted to using illegal drugs.

BY YOON SO-YEON [yoon.soyeon@joongang.co.kr]