South Korea's impeached President Yoon Suk Yeol refused to be questioned by investigators on Monday under a probe into whether he committed insurrection, as dozens of his supporters faced being charged over a violent rampage on a court building.

South Korea's impeached President Yoon Suk Yeol had his mug shot taken and underwent a physical check before spending his first night in jail as a criminal suspect, a prison officer said Monday.

Since police broke up a crowd of Yoon's supporters blocking the court gate in the morning, thousands of supporters surrounded the court after the hearing began at around 2 p.m. (0500 GMT) behind a police barricade chanting "release the president".