SEOUL (Kyodo) -- South Korea's parliament voted on Friday to pass an impeachment motion against Acting President and Prime Minister Han Duck Soo, deepening the turmoil in the country where already-impeached President Yoon Suk Yeol awaits a trial that will decide his political fate.

Han's suspension from his duties elevated Deputy Prime Minister Choi Sang Mok to become South Korea's second acting president in less than two weeks. Choi said the government will do its utmost to stabilize state affairs in his message to the public.

Also on the same day, the Constitutional Court held its first preparatory hearing for the impeachment of Yoon over his short-lived martial law declaration early this month, vowing to proceed quickly on the impeachment trial.

The impeachment motion against Han, which all 192 lawmakers present unanimously voted to pass, was submitted by the opposition Democratic Party the previous day after he refused to appoint additional justices to the Constitutional Court. There are currently six justices at the Constitutional Court, with three seats vacant.

According to South Korea's Constitution, an impeachment motion against a president requires two-thirds of lawmakers' votes to be passed, while all other bills need just half. The National Assembly has 300 seats.

The largest opposition party also listed Han's refusal to sign bills for special counsel investigations into Yoon's imposition of martial law, as well as corruption allegations involving the president's wife, as grounds for introducing the motion.

"I respect the National Assembly's decision, and to not add any more chaos and uncertainties, I will suspend all duties and wait for the Constitutional Court's quick and wise decision," Han said in a statement after the motion was passed.

As for Yoon, the court must decide whether to approve his impeachment or reinstate him within 180 days of the assembly's passage of the motion against him on Dec. 14.

Yoon, whose authority has been suspended, has not cooperated with the court, refusing to accept its documents, including an order to submit the minutes of a Cabinet meeting held before declaring martial law and the text of the decree.

The court responded on Monday by deeming the documents delivered, allowing the preparatory hearing to proceed as scheduled.

The president, meanwhile, has not received the third summons from the joint investigation team, after defying its request to appear at the Corruption Investigation Office for High-Ranking Officials on Dec. 18 and Wednesday, the team said.

The team, comprising members of the corruption investigation office, the police and the defense ministry, is investigating his martial law declaration, through which he allegedly incited an insurrection. The lawyers from Yoon's side have been saying they will prioritize impeachment trials over the investigation.

The corruption investigation office plans to consider requesting a court warrant to detain Yoon if he fails to appear even on Sunday as requested in the third summons, South Korea's Yonhap News Agency reported.

Yoon declared martial law on the night of Dec. 3, but it was rescinded six hours later after lawmakers swiftly convened in the National Assembly and voted to lift it.

Opposition parties submitted the impeachment motion to the parliament, accusing Yoon of failing to meet constitutional requirements in imposing martial law.