South Korea’s arrested President Yoon Suk Yeol did not attend a second day of questioning by investigators on Thursday, further stonewalling a criminal probe into whether he committed insurrection with his bid to impose martial law.

Yoon on Wednesday became the first sitting South Korean president to be arrested and was held at the Seoul Detention Centre after refusing to cooperate.

He remained in the centre on Thursday, with his lawyer citing his health as a factor for his absence from the questioning. The investigators did not elaborate on why they did not compel him to attend.

Authorities have 48 hours to question the suspended president, after which they must release him or seek a warrant to detain him for up to 20 days. That countdown has been paused, however, as his lawyers have asked a court to review the legality of the arrest.

Yoon’s refusal to cooperate with investigators comes as the Constitutional Court held a second hearing in his impeachment trial to determine whether to remove him permanently or reinstate his presidential powers.

South Korea is grappling with its worst political crisis in decades, sparked by Yoon’s brief attempt to impose martial law on December 3 that was voted down by parliament.

In opening arguments at the Constitutional Court, an opposition Democratic Party lawmaker condemned Yoon for “the December 3 insurrection” and said Yoon and a small number of supporters had sought to stoke chaos by refusing to accept his arrest warrant.

“This impeachment trial decides whether or not to bring someone like this back to the position of commander-in-chief in control of the military,” said Jung Chung-rae, the lawmaker who heads parliament’s Legislation and Judiciary Committee.

In response, one of Yoon's defence team said his impeachment was not intended to defend the constitution but for the opposition “to use the majority power of parliament to usurp the position of the president.”

The DP used its majority in parliament to vote to impeach Yoon, although some 12 lawmakers from his own party also voted in favour.

Yoon’s legal team has denied he masterminded an insurrection, a crime in South Korea punishable by life imprisonment or even technically by the death penalty.

The last executions in South Korea were in 1997, for criminal offences such as murder.

Opinion polls conducted by Realmeter on December 4, the day after Yoon’s martial law declaration, showed 73.6 percent supported Yoon’s impeachment. Its latest survey from January 9-10 showed support for Yoon’s ruling party rose to 40.8 percent, catching up with the DP which posted 42.2 percent.

Yoon's lawyer Cho Dae-hyen said the suspended president’s decision to declare martial law had been made in good faith based on his view that the country was in a state of emergency.

Another of Yoon’s lawyers, Bae Jin-han, said: “Some say ‘you get impeached if you breathe’ nowadays.”

Yoon’s arrest ended a weeks-long standoff with authorities after police swooped before dawn on his fortified hillside villa in Seoul, to the dismay of supporters at the site.

Yoon said he turned himself in for questioning to prevent what he called the risk of “unsavoury bloodshed”, though he continued to protest that it was an illegal investigation and invalid arrest warrant.

Protesters Support Yoon

Yoon has so far refused to talk to investigators who had prepared a questionnaire of more than 200 pages, an official from the Corruption Investigation Office for High-ranking Officials (CIO) leading the criminal inquiry said.

His questioning had been due to resume at 2 pm (0500 GMT) on Thursday, but the CIO said that they had been informed by Yoon's side that he would not attend.

Yonhap cited Yoon Kab-keun, one of Yoon’s lawyers, as saying that his health was a factor and saying further questioning was pointless, without elaborating.

A small crowd of protesters supporting Yoon gathered and sat on a road outside the CIO office, calling the president's arrest illegitimate.

His 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.

Yoon’s legal team on Thursday filed a complaint over the warrant with the prosecutors’ office against the CIO chief and some police officials.

The political crisis has reverberated across Asia’s fourth-largest economy and piled pressure on the won currency.

South Korea’s central bank governor said on Thursday that the most important factor determining the health of the economy in coming months was whether the political chaos stabilised.

“That is why a normalisation of the political process is way more important than lowering interest rates a month earlier or later,” said Rhee Chang-yong, speaking after the Bank of Korea unexpectedly held policy interest rates steady at 3.00 percent on Thursday, defying analyst expectations of a cut in rates.