SEOUL - South Korea's presidential security service refused to receive documents about President Yoon Suk-yeol's impeachment trial from the constitutional court, multiple media outlets said Wednesday.

The court sent relevant documents, including Yoon's impeachment resolution passed by the National Assembly last Saturday, to the presidential residence Monday, but the presidential security service refused to receive them Tuesday.

The court's spokesperson said it was unprecedented, noting that the court was reviewing how to deliver documents.

The court ordered the impeached Yoon to submit cabinet meeting minutes and a decree related to the martial law, which was declared by Yoon on the night of Dec 3 but was repealed by the National Assembly hours later.

READ MORE: Parliament strips Yoon of powers; court to make final call

Yoon's legal defense counsel said Tuesday that the embattled president will confidently express his position in court when public hearings are held, indicating Yoon will appear at the constitutional court's impeachment trial when the hearings begin.

The constitutional court planned to hold the first preliminary hearing on the impeachment on Dec 27.

Meanwhile, South Korea's prosecution has decided to transfer Yoon's case to the corruption investigative unit, multiple media outlets said Wednesday.

The Supreme Prosecutors' Office consulted with the Corruption Investigation Office for High-ranking Officials (CIO) and decided to transfer the case to the CIO.

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Controversy emerged over investigations into Yoon, for which various investigative agencies competed for the lead in the investigations.

Prosecutors launched a special investigation unit for Yoon's case, while the CIO set up a joint investigation unit with police and the defense ministry.

The joint investigation unit will probe charges of the impeached president and the interior minister, while the special investigation unit will look into charges of others involved in the martial law imposition.

ALSO READ: South Korea's President Yoon impeached over martial law bid

Yoon was named by investigative agencies as a suspect on rebellion charge following his martial law imposition.

Yoon said in his televised address on Dec 12 that his martial law imposition was an "act of governance" to protect against the "legislative dictatorship" of the majority opposition.