South Korean President Yoon Suk-yeol said on Thursday his December 3 martial law order was a presidential decision to "protect the country's constitutional order from the opposition's parliamentary dictatorship," as he is set to face a second impeachment vote over the controversial move.

Defending his short-lived martial law declaration, which drew widespread calls for his resignation, Yoon said the move was legal, and he's not trying to destroy the constitution.

It is "an act of government administration and not subject to judicial review," he said in a televised address.

Yoon is now the subject of a criminal investigation into insurrection allegations and is banned from leaving the country, while former Defense Minister Kim Yong-hyun, a close confidant of Yoon, has been arrested as part of the investigation.

"I'll face impeachment, investigations or whatever comes," Yoon said.

The second impeachment vote, expected to be held on Saturday, is looking less likely to be in Yoon's favor, as the leader of his own party said the president had shown no signs of resigning and must be impeached.

More members of the ruling party have signaled they would take part in Saturday's vote, drawing a contrast to last week's failed impeachment vote, which was boycotted by most of the party.

"I will fight to the end," Yoon said near the end of his televised speech.