South Korea's arrested President Yoon Suk Yeol will not attend a new round of questioning by investigators on Friday, his lawyer said, as authorities face an imminent deadline to obtain a warrant to extend his detention or release the embattled leader.

In order to hold Yoon in custody for longer, investigators are expected on Friday to ask a court to approve a detention warrant for up to 20 days, legal experts said.

On Wednesday, Yoon became the first sitting South Korean president to be arrested, over a probe into whether he committed insurrection when he briefly imposed martial law in early December. He is being held at the Seoul Detention Centre.