South Korea's ousted premier said Thursday that he had opposed suspended President Yoon Suk Yeol's declaration of martial law, testifying for the first time at his former boss's impeachment trial about the events of a night that threw the country into turmoil.

South Korean President Yoon Suk Yeol contested his arrest on rebellion charges in one court and pleaded to preserve his presidency in the other, both cases related to his brief imposition of martial law.

South Korea's impeached President Yoon Suk Yeol appeared in a Seoul court on Thursday for his first trial hearing on charges of insurrection in the country's first criminal prosecution of an incumbent leader.