The development comes hours before the main liberal opposition Democratic Party submits a new motion to impeach Yoon on the martial law introduction. The party said it aims to put the motion on a floor vote on Saturday.

Earlier, Yoon's former defence minister, Kim Yong Hyun, was arrested after a Seoul court approved an arrest warrant for him on allegations of playing a key role in rebellion and committing abuse of power. Kim became the first person arrested over the December 3 martial law decree.

Opposition parties and many experts say the martial law decree was unconstitutional. They say a president is by law allowed to declare martial law only during “wartime, war-like situations or other comparable national emergency states” and South Korea wasn't in such a situation. They argue that deploying troops to seal the National Assembly to suspend its political activities amounted to rebellion because the South Korean Constitution doesn't allow a president to use the military to suspend parliament in any situation.

In his martial law announcement, the conservative Yoon stressed a need to rebuild the country by eliminating “shameless North Korea followers and anti-state forces,” a reference to his liberal rivals who control parliament. Since taking office in 2022, Yoon has had near-constant friction with the main liberal opposition Democratic Party, which introduced motions to impeach some of his top officials and launched a political offensive over scandals involving Yoon and his wife.

Yoon avoided impeachment last Saturday after most governing party lawmakers boycotted a floor vote in the National Assembly.

If Yoon is impeached, his presidential powers would be suspended until the Constitutional Court decides whether to restore his powers or remove him from office. If he is dismissed from office, a new presidential election would be required.