SEOUL - South Korea's corruption investigative body said Monday that impeached President Yoon Suk-yeol defied its second request to appear for questioning over his martial law imposition.

The Corruption Investigation Office for High-ranking Officials (CIO) said in a short notice that both the presidential office and residence had yet to receive the second request by mail and e-mail to appear on Dec 25 for questioning, which was sent on Dec 20.

Yoon reportedly had yet to submit documents for the appointment of his defense counsel.

The joint investigation unit, composed of the CIO, the police and the defense ministry's investigation headquarters, will allegedly review whether to send the third request for questioning or seek an arrest warrant.

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Yoon said in a televised address on Dec 12 that he would not avoid his legal and political responsibility for the martial law that was declared by Yoon on the night of Dec 3 but was revoked by the National Assembly hours later.

The impeachment motion against Yoon was passed in the National Assembly on Dec 14 and was delivered to the constitutional court to deliberate it for up to 180 days, during which Yoon's presidential power will be suspended. 

Meanwhile, South Korea's constitutional court said Monday that it will hold the first pretrial hearing over Yoon's impeachment on Friday as scheduled.

A court official told a televised press conference that the first preliminary hearing would be held on Dec 27 as planned as the court deemed the impeachment notice delivered to Yoon, who repeatedly defied the delivery.

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The official said the delivery was already effective on Dec 20 when all relevant documents arrived, calling for Yoon to send his written answers to the court by Friday.

The presidential security service had refused to receive the documents related to Yoon's impeachment trial, such as request to appear in court and schedule for pretrial hearings.