South Korea's opposition party moves to impeach acting President Han Duck-soo

South Korea's opposition party plans to impeach acting President Han Duck-soo, escalating a constitutional crisis linked to martial law

South Korea's main opposition party said it will introduce a bill to impeach acting President Han Duck-soo on Thursday and hold a vote on Friday, a move that could deepen the country's constitutional crisis triggered by a short-lived martial law.

The largest opposition party in South Korea said that it would present a measure to remove acting President Han Duck-soo from office. (REUTERS)

The opposition Democratic Party had threatened to impeach Han if he does not immediately appoint three justices to fill the vacancies at the Constitutional Court. Parliament voted in favour of three nominees on Thursday, but they have yet to be formally appointed by Han.

The court is trying the impeachment of President Yoon Suk Yeol over his Dec. 3 declaration of martial law.

"It has become clear that Prime Minister and acting President Han Duck-soo does not have the qualification or the will to safeguard the Constitution," Democratic Party floor leader Park Chan-dae said in a statement.

If Han is impeached, the finance minister will assume the acting presidency. The Democratic Party has majority control of parliament, but there is disagreement between the parties and some constitutional scholars over whether a simple majority or a two-thirds vote is needed to impeach the acting president.

Han said earlier on Thursday that he will not appoint the justices until political parties reach agreement on the appointments, because for him to do so without political consensus will harm constitutional order.

Two of the proposed appointees for the Constitutional Court up for the vote on Thursday were nominated by the Democratic Party and one by Han's ruling People Power Party. The ruling party objected to the breakdown, saying it had not agreed to it.

Han has been under pressure to make the appointments, but political parties have disagreed on whether he has the authority to do so as acting president.

The court is set to hold its first hearing on Friday in the trial to decide whether to remove Yoon or reinstate him.

Under the constitution, six justices must agree to remove an impeached president, meaning the current justices must vote unanimously to remove Yoon. The court has said it can deliberate without the full bench.

Yoon, who was impeached by parliament on Dec. 14 in a vote joined by some members of his centre-right party, has not submitted legal papers as requested by the court as of Thursday, court spokesperson Lee Jean told a media briefing.

On Wednesday, he did not respond to the latest summons for questioning in a separate criminal investigation.

Yoon's repeated defiance has sparked criticism and calls from the opposition for his arrest.