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.

Yoon was arrested in a dawn raid last week, becoming the first sitting South Korean president to be detained in a criminal probe on insurrection charges over his botched declaration of martial law.

A court approved his formal arrest warrant Sunday, citing concerns he would destroy evidence, and Yoon transitioned from a temporary detainee to a criminal suspect facing an indictment and trial.

Yoon was assigned a 12-square-meter (129-square-feet) cell at Seoul Detention Center in Uiwang on Sunday, according to Shin Yong-hae, commissioner general of the Korea Correctional Service.

He was "assigned to one of the standard rooms used by regular inmates," Shin told lawmakers during a parliamentary session.

Yoon's cell, which typically holds five or six people, is similar in size to those where past presidents have been detained, Shin said.

The suspended leader, whose powers have been transferred to an acting president but who remains the sitting head of state, also had his mug shot taken and underwent a physical examination like his fellow inmates, Shin said.

"The individual cooperated well with the procedures without any particular issues," Shin said.

According to prison regulations, Yoon will change from his normal clothes into a khaki prison uniform and will be assigned an inmate number.

Prison officials have said his cell includes a small table for eating and studying, a small shelf, a sink, and a toilet. It also includes a television, but viewing time is strictly restricted.

Inmates are allowed an hour of exercise daily and one shower a week, but local media report that authorities will attempt to prevent him from coming into contact with other inmates.

His personal security detail will accompany him whenever he leaves his cell, reports say.

Court Attack

Yoon plunged South Korea into political chaos with his December 3 martial law declaration, which lasted just six hours before lawmakers voted it down. He was later impeached and stripped of duties.

He faces a Constitutional Court case deciding whether to uphold his impeachment, as well as a criminal investigation on insurrection charges, over which he has been detained.

Yoon has claimed the probe is illegal and resisted arrest for weeks, vowing to "fight to the end." His die-hard supporters attacked the court building Sunday after it extended Yoon's detention.

Dozens of people, including YouTube streamers, have been arrested over a riot at a Seoul court, police said Monday, with 51 police officers injured, including some with head injuries and fractures.

Up to 35,000 of his supporters gathered outside the court on Saturday, according to a police document seen by AFP.

After the formal arrest warrant was issued early Sunday, around 300 people gathered near the rear entrance and began "throwing objects such as glass bottles, rocks, and chairs into the court grounds," according to the police report.

"Some 100 protesters entered the court premises, smashing windows on the first floor, damaging the walls, and entering the building," said the police.

Yoon declined to attend questioning Monday, his lawyers said, with the Corruption Investigation Office (CIO), the body overseeing the probe, stating it would consider a "forced summons."