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SEOUL -- South Korean prosecutors have asked the impeached President Yoon Suk-yeol to appear for questioning over his martial law imposition by Dec 21, Yonhap news agency said Tuesday.

The prosecution's special investigation team delivered a summons to Yoon's side Monday, calling for Yoon to appear for questioning over charges of insurrection and abuse of power by Saturday.

The prosecution sent an official letter last week to the presidential side, asking Yoon to appear at the Seoul Central District Prosecutors' Office at 10:00 a.m. local time (0100 GMT) Sunday.

Yoon defied the subpoena last week, reportedly saying that his defense counsel had yet to be formed.

The prosecution was quoted as saying that if Yoon does not comply with the second summons order, it will consider seeking an arrest warrant.

If Yoon complies with the summons, he will become the country's first sitting president to appear at the prosecutors' office for questioning as a criminal suspect.

Separately, a joint investigation unit of the police, the defense ministry and the Corruption Investigation Office for High-ranking Officials asked Yoon to appear for questioning on Wednesday, but both the presidential office and residence refused to receive the summons.

Yoon was named by investigative agencies as a suspect on a rebellion charge following his martial law imposition on the night of Dec. 3 which was revoked by the National Assembly hours later.

The second motion to impeach Yoon was passed through 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.