SEOUL -- South Korea's anti-corruption agency said on Thursday it has decided to refer the arrested President Yoon Suk-yeol's "insurrection case" to the prosecution, according to multiple media outlets.

The Corruption Investigation Office for High-ranking Officials (CIO) decided to transfer the case to the Seoul Central District Prosecutors' Office, demanding the indictment of Yoon as the CIO has no right to indict the president.

Yoon was apprehended in the presidential office on Jan 15, becoming the country's first sitting president to be arrested. A warrant to extend the detention of Yoon for up to 20 days, including the arrest period, was granted by a Seoul court on Jan 19.

The CIO and the prosecution agreed to jointly investigate Yoon's "insurrection" charge by questioning the impeached president for 10 respective days.

The prosecution was widely expected to indict Yoon for the "insurrection" and other charges around Feb 5.

Yoon rejected the CIO's repeated call to appear for questioning.

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

Yoon, who was named by investigative agencies as a suspected ringleader on "insurrection" charge, declared a martial law on the night of Dec 3, but it was revoked by the National Assembly hours later.