SEOUL -- South Korea's constitutional court on Tuesday called for an early appointment of justices to fill three vacancies on the nine-member bench for President Yoon Suk-yeol's impeachment trial over his martial law imposition.

A spokesperson of the court told a televised press briefing that the incumbent justices urged the "rapid completion" of the constitutional court during a meeting on Monday.

She noted that the six justices maintained their position of putting Yoon's impeachment trial as a top priority.

On Dec 26, the country's parliament voted for the appointment of the three justices, two of which were nominated by the main opposition Democratic Party, while one was nominated by the ruling People Power Party.

The appointment of the three justices, which was passed in the opposition-controlled National Assembly, is required to be ceremonially approved by the president.

Economy and Finance Minister Choi Sang-mok, who doubles as deputy prime minister for economic affairs, became an acting president following the impeachment of both President Yoon and Prime Minister Han Duck-soo.

Han was impeached by the National Assembly after officially refusing to ratify the appointment of the justices.

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 is suspended.

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agencies as a suspect on insurrection charge, declared an emergency martial law on the night of Dec 3, but it was revoked by the National Assembly hours later.

To oust Yoon from office, at least six out of nine constitutional court justices are required to uphold the impeachment motion.