SEOUL: An unidentified man died after setting himself on fire on Wednesday near South Korea’s corruption investigation office, where impeached President Yoon Suk Yeol was being interrogated over insurrection allegations, the Yonhap News Agency reported.

The incident happened just after 8pm local time (1100 GMT), the news agency said, citing police. The man was taken to hospital by firefighters but later died.

Reuters could not immediately reach the police or fire services for comment.

An official at a fire station said the incident happened a few kilometres from the investigations building but did not have specific details.

At least three fire engines and an ambulance, with sirens blaring, passed by the anti-graft offices just after 8pm, according to a Reuters witness.

Scores of people protesting Yoon’s arrest, related to his stunning decision to declare martial law on December 3 that plunged the country into political turmoil, were still gathered outside the offices at the time of the incident.

Yoon is under investigation after he was arrested and questioned by authorities on Wednesday in relation to a criminal insurrection investigation, and he said he was only cooperating with what he called an illegal probe to avoid violence.

Since lawmakers voted to impeach and remove him from duties after his short-lived December 3 declaration of martial law, Yoon has been holed up at his hillside residence, guarded by a small army of presidential security that blocked a previous arrest attempt.

He agreed to come in for questioning after more than 3,000 police officers determined to arrest him marched on his residence early on Wednesday.

“I decided to respond to the CIO’s investigation — despite it being an illegal investigation — to prevent unsavoury bloodshed,” Yoon said in a statement, referring to the Corruption Investigation Office for High-ranking Officials (CIO) that is heading the criminal inquiry.

A prosecutor accompanied Yoon in his car from his home in the upscale district known as Seoul’s Beverly Hills to the austere CIO offices, where he slipped in through a back entrance, avoiding media.

Authorities now have 48 hours to question Yoon after which they must seek a warrant to detain him for up to 20 days or release him.

However, Yoon is refusing to talk and has not agreed to have interviews with investigators recorded on video, a CIO official said. 

The questioning will continue after Yoon finishes a dinner of bean paste soup, the CIO official said, though whether it would continue late into the night had not been decided.

Yoon’s lawyers have said the arrest warrant is illegal because it was issued by a court in the wrong jurisdiction and the team set up to investigate him had no legal mandate to do so. 

A warrant to search Yoon at his residence, a copy of which was seen by Reuters, referred to him as “ringleader of insurrection”.