SEOUL — South Korea's President Yoon Suk-yeol refused to appear for fresh questioning by investigators on Thursday, a day after his arrest over a failed martial law declaration.

The Constitutional Court also opened its second hearing in a trial that will decide whether to uphold Yoon's impeachment, following the dawn raid that made him the country's first-ever sitting president to be detained.

The former star prosecutor, who faces charges of insurrection, was questioned for hours on Wednesday but exercised his right to remain silent before being moved to a detention center.

Investigators from the Corruption Investigation Office, or CIO, resumed Yoon's questioning on Thursday afternoon, but he did not attend.

"President Yoon Suk-yeol's representatives informed the CIO through his legal counsel around 1:50 pm that there is 'no change in his position', indicating his intent not to appear," the CIO said in a statement before the questioning.

Yoon's lawyer confirmed to AFP the leader would not attend, without specifying the reason, but told the Yonhap news agency it was for health reasons.

"President Yoon is not well and fully explained his position yesterday, so there is nothing more to be interrogated about," Yoon Kab-keun, the lawyer, told Yonhap, an apparent reference to his decision not to answer questions on Wednesday.

Wednesday's arrest saw a hundreds-strong force of police and investigators bypass bus barricades, cut barbed wire and scale ladders to get inside the compound where Yoon was surrounded by hundreds of guards.

Yoon said he complied with investigators to avoid "bloodshed" but did not accept the legality of the investigation.

Meanwhile, officials were trying to secure a new warrant that could hold him for longer than 48 hours.

If investigators successfully obtain that warrant, they are expected to be given a 20-day extension to the leader's detention to allow time to formalize an indictment against him.

South Korea's opposition Democratic Party celebrated Yoon's detention, while the parliament speaker said it was time to stabilize the country after weeks of turmoil.

However, Yoon's lawyers have filed for a review of the warrant used to arrest him.

Experts say Yoon's legal team appears to be trying to drag out the arrest process to his benefit.

Opinion polls show a majority of South Koreans support impeaching Yoon, but the attempts to arrest him appear to have rallied his hardcore supporters.

Agencies Via Xinhua